feat(34-02): extract hardcoded strings from thread/candidate components

- CandidateCard: replace all hardcoded titles and badge text with t()
- CandidateListItem: add useTranslation, replace winner/delete/open labels and +/- Notes badge
- CandidateForm: add useTranslation, replace all form labels, placeholders, validation errors, submit button
- ComparisonTable: move STATUS_LABELS inside component with t(), replace all ATTRIBUTE_ROWS labels, View button, impact row labels
- StatusBadge: refactor STATUS_CONFIG to STATUS_ICONS + runtime STATUS_LABELS via t()
- CreateThreadModal: replace title, thread name label, category label, placeholder, cancel/submit buttons, error messages
- AddToThreadModal: replace modal titles, labels, placeholders, back/cancel/submit buttons, error messages
- threads.json: extend candidateForm with category, notes, pros, cons, product link labels and all placeholders

src/client/components/CreateThreadModal.tsx

@@ -1,9 +1,11 @@
 import { useEffect, useState } from "react";
+import { useTranslation } from "react-i18next";
 import { useCategories } from "../hooks/useCategories";
 import { useCreateThread } from "../hooks/useThreads";
 import { useUIStore } from "../stores/uiStore";
 
 export function CreateThreadModal() {
+	const { t } = useTranslation(["threads", "common"]);
 	const isOpen = useUIStore((s) => s.createThreadModalOpen);
 	const closeModal = useUIStore((s) => s.closeCreateThreadModal);
 
@@ -38,11 +40,11 @@ export function CreateThreadModal() {
 		e.preventDefault();
 		const trimmed = name.trim();
 		if (!trimmed) {
-			setError("Thread name is required");
+			setError(t("create.nameRequired"));
 			return;
 		}
 		if (categoryId === null) {
-			setError("Please select a category");
+			setError(t("create.selectCategory"));
 			return;
 		}
 		setError(null);
@@ -55,7 +57,7 @@ export function CreateThreadModal() {
 				},
 				onError: (err) => {
 					setError(
-						err instanceof Error ? err.message : "Failed to create thread",
+						err instanceof Error ? err.message : t("create.createFailed"),
 					);
 				},
 			},
@@ -77,7 +79,7 @@ export function CreateThreadModal() {
 				onClick={(e) => e.stopPropagation()}
 				onKeyDown={() => {}}
 			>
-				<h2 className="text-lg font-semibold text-gray-900 mb-4">New Thread</h2>
+				<h2 className="text-lg font-semibold text-gray-900 mb-4">{t("create.title")}</h2>
 
 				<form onSubmit={handleSubmit} className="space-y-4">
 					<div>
@@ -85,14 +87,14 @@ export function CreateThreadModal() {
 							htmlFor="thread-name"
 							className="block text-sm font-medium text-gray-700 mb-1"
 						>
-							Thread name
+							{t("create.threadName")}
 						</label>
 						<input
 							id="thread-name"
 							type="text"
 							value={name}
 							onChange={(e) => setName(e.target.value)}
-							placeholder="e.g. Lightweight sleeping bag"
+							placeholder={t("create.namePlaceholder")}
 							className="w-full px-3 py-2 border border-gray-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-gray-400 focus:border-transparent"
 						/>
 					</div>
@@ -102,7 +104,7 @@ export function CreateThreadModal() {
 							htmlFor="thread-category"
 							className="block text-sm font-medium text-gray-700 mb-1"
 						>
-							Category
+							{t("create.category")}
 						</label>
 						<select
 							id="thread-category"
@@ -126,14 +128,14 @@ export function CreateThreadModal() {
 							onClick={handleClose}
 							className="px-4 py-2 text-sm font-medium text-gray-700 bg-gray-100 hover:bg-gray-200 rounded-lg transition-colors"
 						>
-							Cancel
+							{t("common:actions.cancel")}
 						</button>
 						<button
 							type="submit"
 							disabled={createThread.isPending}
 							className="px-4 py-2 text-sm font-medium text-white bg-gray-700 hover:bg-gray-800 disabled:opacity-50 rounded-lg transition-colors"
 						>
-							{createThread.isPending ? "Creating..." : "Create Thread"}
+							{createThread.isPending ? t("common:actions.creating") : t("create.createThread")}
 						</button>
 					</div>
 				</form>