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/StatusBadge.tsx

@@ -1,13 +1,14 @@
 import { useEffect, useRef, useState } from "react";
+import { useTranslation } from "react-i18next";
 import { LucideIcon } from "../lib/iconData";
 
-const STATUS_CONFIG = {
-	researching: { icon: "search", label: "Researching" },
-	ordered: { icon: "truck", label: "Ordered" },
-	arrived: { icon: "check", label: "Arrived" },
+const STATUS_ICONS = {
+	researching: "search",
+	ordered: "truck",
+	arrived: "check",
 } as const;
 
-type CandidateStatus = keyof typeof STATUS_CONFIG;
+type CandidateStatus = keyof typeof STATUS_ICONS;
 
 interface StatusBadgeProps {
 	status: CandidateStatus;
@@ -15,10 +16,15 @@ interface StatusBadgeProps {
 }
 
 export function StatusBadge({ status, onStatusChange }: StatusBadgeProps) {
+	const { t } = useTranslation("threads");
 	const [isOpen, setIsOpen] = useState(false);
 	const containerRef = useRef<HTMLDivElement>(null);
 
-	const config = STATUS_CONFIG[status];
+	const STATUS_LABELS: Record<CandidateStatus, string> = {
+		researching: t("statusBadge.researching"),
+		ordered: t("statusBadge.ordered"),
+		arrived: t("statusBadge.arrived"),
+	};
 
 	useEffect(() => {
 		if (!isOpen) return;
@@ -56,14 +62,13 @@ export function StatusBadge({ status, onStatusChange }: StatusBadgeProps) {
 				}}
 				className="inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-xs font-medium bg-gray-100 text-gray-600 hover:bg-gray-200 transition-colors cursor-pointer"
 			>
-				<LucideIcon name={config.icon} size={14} className="text-gray-500" />
-				{config.label}
+				<LucideIcon name={STATUS_ICONS[status]} size={14} className="text-gray-500" />
+				{STATUS_LABELS[status]}
 			</button>
 
 			{isOpen && (
 				<div className="absolute right-0 top-full mt-1 z-20 bg-white border border-gray-200 rounded-lg shadow-lg py-1 min-w-[150px]">
-					{(Object.keys(STATUS_CONFIG) as CandidateStatus[]).map((key) => {
-						const option = STATUS_CONFIG[key];
+					{(Object.keys(STATUS_ICONS) as CandidateStatus[]).map((key) => {
 						const isActive = key === status;
 						return (
 							<button
@@ -79,12 +84,12 @@ export function StatusBadge({ status, onStatusChange }: StatusBadgeProps) {
 								}`}
 							>
 								<LucideIcon
-									name={option.icon}
+									name={STATUS_ICONS[key]}
 									size={14}
 									className={isActive ? "text-gray-700" : "text-gray-400"}
 								/>
 								<span className={isActive ? "text-gray-900" : "text-gray-600"}>
-									{option.label}
+									{STATUS_LABELS[key]}
 								</span>
 								{isActive && (
 									<LucideIcon