feat(i18n): extract strings from navigation, dialogs, onboarding, settings, and login

- Add useTranslation() to TopNav, BottomTabBar, FabMenu, UserMenu
- Internationalize ConfirmDialog, AuthPromptModal, ExternalLinkDialog
- Extract all onboarding flow strings (Welcome, HobbyPicker, ItemBrowser, Review, Done)
- Internationalize settings page (weight unit, currency, API keys, import/export)
- Internationalize login page and root error boundary
- All dialogs in __root.tsx use t() for UI chrome

Phase 34, Plan 02 (core navigation and global UI)

src/client/components/onboarding/OnboardingReview.tsx

@@ -1,3 +1,4 @@
+import { useTranslation } from "react-i18next";
 import { LucideIcon } from "../../lib/iconData";
 
 interface ReviewItem {
@@ -23,6 +24,7 @@ export function OnboardingReview({
 	onSkip,
 	isSubmitting,
 }: OnboardingReviewProps) {
+	const { t } = useTranslation("onboarding");
 	// Group by category
 	const grouped = new Map<string, ReviewItem[]>();
 	for (const item of items) {
@@ -35,12 +37,12 @@ export function OnboardingReview({
 		<div className="flex flex-col items-center justify-center min-h-screen px-8">
 			<div className="max-w-2xl w-full text-center">
 				<h1 className="text-3xl font-bold text-gray-900 mb-2">
-					Your starting collection
+					{t("review.title")}
 				</h1>
 				<p className="text-base text-gray-500 mb-8">
 					{items.length > 0
-						? `${items.length} ${items.length === 1 ? "item" : "items"} ready to add`
-						: "No items selected — you can always add gear later from the catalog."}
+						? t("review.itemsReady", { count: items.length })
+						: t("review.noItemsSelected")}
 				</p>
 
 				{items.length > 0 && (
@@ -101,7 +103,7 @@ export function OnboardingReview({
 							disabled={isSubmitting}
 							className="px-8 py-3 bg-gray-700 hover:bg-gray-800 disabled:opacity-50 text-white font-medium rounded-lg transition-colors"
 						>
-							{isSubmitting ? "Adding..." : "Add to my collection"}
+							{isSubmitting ? t("review.adding") : t("review.addToCollection")}
 						</button>
 					) : (
 						<button
@@ -109,7 +111,7 @@ export function OnboardingReview({
 							onClick={onSkip}
 							className="px-8 py-3 bg-gray-700 hover:bg-gray-800 text-white font-medium rounded-lg transition-colors"
 						>
-							Continue
+							{t("common:actions.continue")}
 						</button>
 					)}
 					{items.length > 0 && (
@@ -118,7 +120,7 @@ export function OnboardingReview({
 							onClick={onSkip}
 							className="text-sm text-gray-400 hover:text-gray-600 transition-colors"
 						>
-							Skip this step
+							{t("common:actions.skipStep")}
 						</button>
 					)}
 				</div>