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/shared/schemas.ts

@@ -36,6 +36,9 @@ export const updateThreadSchema = z.object({
 	categoryId: z.number().int().positive().optional(),
 });
 
+// Candidate status
+export const candidateStatusSchema = z.enum(["researching", "ordered", "arrived"]);
+
 // Candidate schemas (same fields as items)
 export const createCandidateSchema = z.object({
 	name: z.string().min(1, "Name is required"),
@@ -45,6 +48,7 @@ export const createCandidateSchema = z.object({
 	notes: z.string().optional(),
 	productUrl: z.string().url().optional().or(z.literal("")),
 	imageFilename: z.string().optional(),
+	status: candidateStatusSchema.optional(),
 });
 
 export const updateCandidateSchema = createCandidateSchema.partial();