feat(i18n): install react-i18next, create English locale files, and initialize i18n framework

- Install i18next, react-i18next, i18next-browser-languagedetector
- Create 6 namespace JSON files (common, collection, threads, setups, onboarding, settings)
- Initialize i18n with language detection (localStorage + navigator)
- Wire i18n import in main.tsx before React rendering

Phase 34, Plan 01

src/client/lib/i18n.ts

@@ -0,0 +1,39 @@
+import i18n from "i18next";
+import LanguageDetector from "i18next-browser-languagedetector";
+import { initReactI18next } from "react-i18next";
+
+import enCollection from "../locales/en/collection.json";
+import enCommon from "../locales/en/common.json";
+import enOnboarding from "../locales/en/onboarding.json";
+import enSettings from "../locales/en/settings.json";
+import enSetups from "../locales/en/setups.json";
+import enThreads from "../locales/en/threads.json";
+
+i18n
+	.use(LanguageDetector)
+	.use(initReactI18next)
+	.init({
+		resources: {
+			en: {
+				common: enCommon,
+				collection: enCollection,
+				threads: enThreads,
+				setups: enSetups,
+				onboarding: enOnboarding,
+				settings: enSettings,
+			},
+		},
+		supportedLngs: ["en", "de"],
+		fallbackLng: "en",
+		defaultNS: "common",
+		interpolation: {
+			escapeValue: false,
+		},
+		detection: {
+			order: ["localStorage", "navigator"],
+			lookupLocalStorage: "gearbox-language",
+			caches: ["localStorage"],
+		},
+	});
+
+export default i18n;

src/client/locales/en/collection.json

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+{
+	"title": "Collection",
+	"gear": "Gear",
+	"planning": "Planning",
+	"empty": {
+		"title": "Your collection is empty",
+		"description": "Start cataloging your gear by adding your first item. Track weight, price, and organize by category.",
+		"addFirst": "Add your first item"
+	},
+	"form": {
+		"name": "Name",
+		"nameRequired": "Name *",
+		"namePlaceholder": "e.g. Osprey Talon 22",
+		"weight": "Weight (g)",
+		"weightPlaceholder": "e.g. 680",
+		"price": "Price ($)",
+		"pricePlaceholder": "e.g. 129.99",
+		"quantity": "Quantity",
+		"category": "Category",
+		"notes": "Notes",
+		"notesPlaceholder": "Any additional notes...",
+		"productLink": "Product Link",
+		"urlPlaceholder": "https://..."
+	},
+	"classification": {
+		"ultralight": "Ultralight",
+		"light": "Light",
+		"medium": "Medium",
+		"heavy": "Heavy"
+	}
+}

src/client/locales/en/common.json

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+{
+	"nav": {
+		"home": "Home",
+		"collection": "Collection",
+		"setups": "Setups",
+		"discover": "Discover",
+		"settings": "Settings",
+		"search": "Search",
+		"searchPlaceholder": "Search catalog...",
+		"profile": "Profile"
+	},
+	"actions": {
+		"save": "Save",
+		"cancel": "Cancel",
+		"delete": "Delete",
+		"edit": "Edit",
+		"create": "Create",
+		"close": "Close",
+		"back": "Back",
+		"confirm": "Confirm",
+		"continue": "Continue",
+		"tryAgain": "Try again",
+		"dismiss": "Dismiss",
+		"saving": "Saving...",
+		"deleting": "Deleting...",
+		"creating": "Creating...",
+		"loading": "Loading...",
+		"addItem": "Add Item",
+		"saveChanges": "Save Changes",
+		"revoke": "Revoke",
+		"skipStep": "Skip this step"
+	},
+	"errors": {
+		"somethingWentWrong": "Something went wrong",
+		"unexpectedError": "An unexpected error occurred",
+		"nameRequired": "Name is required",
+		"positiveNumber": "Must be a positive number",
+		"validUrl": "Must be a valid URL (https://...)"
+	},
+	"auth": {
+		"signIn": "Sign in",
+		"signOut": "Sign out",
+		"joinGearBox": "Join GearBox",
+		"signInToGearBox": "Sign in to GearBox",
+		"signInDescription": "To manage your own collection, sign in or sign up.",
+		"createAccount": "Create account",
+		"redirectDescription": "You will be redirected to sign in with your account."
+	},
+	"confirm": {
+		"deleteItem": "Delete Item",
+		"deleteItemMessage": "Are you sure you want to delete <bold>{{name}}</bold>? This action cannot be undone.",
+		"deleteCandidate": "Delete Candidate",
+		"deleteCandidateMessage": "Are you sure you want to delete <bold>{{name}}</bold>? This action cannot be undone.",
+		"pickWinner": "Pick Winner",
+		"pickWinnerMessage": "Pick <bold>{{name}}</bold> as the winner? This will add it to your collection and archive the thread."
+	},
+	"externalLink": {
+		"title": "You are about to leave GearBox",
+		"redirectMessage": "You will be redirected to:"
+	},
+	"fab": {
+		"addToCollection": "Add to Collection",
+		"startNewThread": "Start New Thread",
+		"newSetup": "New Setup"
+	},
+	"empty": {
+		"noResults": "No results found",
+		"noItems": "No items match your search"
+	},
+	"stats": {
+		"items": "Items",
+		"totalWeight": "Total Weight",
+		"totalSpent": "Total Spent"
+	},
+	"filter": {
+		"showing": "Showing {{filtered}} of {{total}} items",
+		"searchItems": "Search items...",
+		"allCategories": "All Categories"
+	}
+}

src/client/locales/en/onboarding.json

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+{
+	"welcome": {
+		"title": "Welcome to GearBox",
+		"subtitle": "Tell us what you're into, and we'll help you set up your collection with gear that people actually use.",
+		"cta": "Let's go"
+	},
+	"hobby": {
+		"title": "What are you into?",
+		"subtitle": "Pick one or more — we'll show you popular gear for each.",
+		"continue": "Continue"
+	},
+	"items": {
+		"title": "Popular gear for {{hobby}}",
+		"titleMultiple": "Popular gear for your hobbies",
+		"subtitle": "Tap items you already own. We'll add them to your collection.",
+		"noCatalog": "No gear cataloged yet",
+		"noCatalogDescription": "We're still building our catalog for this hobby. You can skip this step and add gear manually later.",
+		"reviewCount": "Review {{count}} items",
+		"reviewCount_one": "Review {{count}} item"
+	},
+	"review": {
+		"title": "Your starting collection",
+		"itemsReady": "{{count}} items ready to add",
+		"itemsReady_one": "{{count}} item ready to add",
+		"noItemsSelected": "No items selected — you can always add gear later from the catalog.",
+		"addToCollection": "Add to my collection",
+		"adding": "Adding..."
+	},
+	"done": {
+		"title": "You're all set!",
+		"subtitle": "Your collection is ready. Browse the catalog anytime to discover more gear.",
+		"cta": "Start exploring"
+	}
+}

src/client/locales/en/settings.json

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+{
+	"title": "Settings",
+	"language": {
+		"title": "Language",
+		"description": "Change the display language of the app"
+	},
+	"weightUnit": {
+		"title": "Weight Unit",
+		"description": "Choose the unit used to display weights across the app"
+	},
+	"currency": {
+		"title": "Currency",
+		"description": "Changes the currency symbol displayed. This does not convert values."
+	},
+	"apiKeys": {
+		"title": "API Keys",
+		"description": "API keys allow programmatic access to GearBox (e.g., from Claude Desktop or scripts).",
+		"copyWarning": "Copy this key now — it won't be shown again:",
+		"namePlaceholder": "Key name (e.g., claude-desktop)"
+	},
+	"importExport": {
+		"title": "Import / Export",
+		"description": "Export your gear collection as a CSV file, or import items from a CSV.",
+		"export": "Export CSV",
+		"import": "Import CSV",
+		"importing": "Importing...",
+		"imported": "{{count}} items imported.",
+		"imported_one": "{{count}} item imported.",
+		"newCategories": "New categories: {{categories}}",
+		"noItemsFound": "No items found in the CSV."
+	}
+}

src/client/locales/en/setups.json

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+{
+	"title": "Setups",
+	"create": "New Setup",
+	"empty": {
+		"title": "No setups yet",
+		"description": "Create a setup to organize gear for specific trips or activities."
+	},
+	"card": {
+		"items": "{{count}} items",
+		"items_one": "{{count}} item",
+		"weight": "Weight",
+		"price": "Price"
+	},
+	"share": {
+		"title": "Share Setup",
+		"shareLinks": "Share Links",
+		"createLink": "Create Link",
+		"noLinks": "No share links yet",
+		"copyLink": "Copy link",
+		"revokeLink": "Revoke link",
+		"copied": "Copied!",
+		"noExpiration": "No expiration",
+		"expired": "Expired",
+		"expiresToday": "Expires today",
+		"expiresTomorrow": "Expires tomorrow",
+		"expiresInDays": "Expires in {{days}} days",
+		"daysOption": "{{days}} days",
+		"deactivateWarning": "Switching to private will deactivate all share links. They can be reactivated by switching back."
+	},
+	"visibility": {
+		"private": "Private",
+		"privateDescription": "Only you can access",
+		"link": "Link sharing",
+		"linkDescription": "Anyone with the link",
+		"public": "Public",
+		"publicDescription": "Visible on your profile"
+	},
+	"impact": {
+		"title": "Impact Preview",
+		"adding": "Adding",
+		"removing": "Removing"
+	}
+}

src/client/locales/en/threads.json

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+{
+	"title": "Research Threads",
+	"create": {
+		"title": "New Thread",
+		"threadName": "Thread name",
+		"namePlaceholder": "e.g. Lightweight sleeping bag",
+		"category": "Category",
+		"nameRequired": "Thread name is required",
+		"selectCategory": "Please select a category",
+		"createFailed": "Failed to create thread",
+		"createThread": "Create Thread"
+	},
+	"status": {
+		"active": "Active",
+		"researching": "Researching",
+		"ordered": "Ordered",
+		"arrived": "Arrived",
+		"resolved": "Resolved",
+		"archived": "Archived"
+	},
+	"candidate": {
+		"name": "Name",
+		"price": "Price",
+		"weight": "Weight",
+		"url": "URL",
+		"pros": "Pros",
+		"cons": "Cons",
+		"notes": "Notes",
+		"addCandidate": "Add Candidate"
+	},
+	"comparison": {
+		"weight": "Weight",
+		"price": "Price",
+		"pros": "Pros",
+		"cons": "Cons"
+	},
+	"resolve": {
+		"title": "Pick Winner",
+		"message": "Pick <bold>{{name}}</bold> as the winner? This will add it to your collection and archive the thread."
+	},
+	"empty": {
+		"noThreads": "No research threads yet",
+		"noCandidates": "No candidates yet"
+	}
+}

src/client/main.tsx

@@ -1,3 +1,4 @@
+import "./lib/i18n";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { createRouter, RouterProvider } from "@tanstack/react-router";
 import { StrictMode } from "react";