feat(08-01): add status column to threadCandidates and wire through backend

- Schema: status TEXT NOT NULL DEFAULT 'researching' on thread_candidates
- Zod: candidateStatusSchema enum (researching/ordered/arrived) added to createCandidateSchema
- Service: getThreadWithCandidates selects status, createCandidate sets status, updateCandidate accepts status
- Client hooks: CandidateWithCategory and CandidateResponse types include status field
- Migration generated and applied

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/server/services/thread.service.ts

@@ -72,6 +72,7 @@ export function getThreadWithCandidates(db: Db = prodDb, threadId: number) {
 			notes: threadCandidates.notes,
 			productUrl: threadCandidates.productUrl,
 			imageFilename: threadCandidates.imageFilename,
+			status: threadCandidates.status,
 			createdAt: threadCandidates.createdAt,
 			updatedAt: threadCandidates.updatedAt,
 			categoryName: categories.name,
@@ -149,6 +150,7 @@ export function createCandidate(
 			notes: data.notes ?? null,
 			productUrl: data.productUrl ?? null,
 			imageFilename: data.imageFilename ?? null,
+			status: data.status ?? "researching",
 		})
 		.returning()
 		.get();
@@ -165,6 +167,7 @@ export function updateCandidate(
 		notes: string;
 		productUrl: string;
 		imageFilename: string;
+		status: "researching" | "ordered" | "arrived";
 	}>,
 ) {
 	const existing = db