test(02-01): add failing tests for thread service

- Add threads and threadCandidates tables to Drizzle schema
- Add Zod schemas for thread/candidate/resolve validation
- Add Thread/ThreadCandidate types to shared types
- Update test helper with threads and thread_candidates tables
- Write comprehensive failing tests for thread service

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/db/schema.ts

@@ -28,6 +28,41 @@ export const items = sqliteTable("items", {
     .$defaultFn(() => new Date()),
 });
 
+export const threads = sqliteTable("threads", {
+  id: integer("id").primaryKey({ autoIncrement: true }),
+  name: text("name").notNull(),
+  status: text("status").notNull().default("active"),
+  resolvedCandidateId: integer("resolved_candidate_id"),
+  createdAt: integer("created_at", { mode: "timestamp" })
+    .notNull()
+    .$defaultFn(() => new Date()),
+  updatedAt: integer("updated_at", { mode: "timestamp" })
+    .notNull()
+    .$defaultFn(() => new Date()),
+});
+
+export const threadCandidates = sqliteTable("thread_candidates", {
+  id: integer("id").primaryKey({ autoIncrement: true }),
+  threadId: integer("thread_id")
+    .notNull()
+    .references(() => threads.id, { onDelete: "cascade" }),
+  name: text("name").notNull(),
+  weightGrams: real("weight_grams"),
+  priceCents: integer("price_cents"),
+  categoryId: integer("category_id")
+    .notNull()
+    .references(() => categories.id),
+  notes: text("notes"),
+  productUrl: text("product_url"),
+  imageFilename: text("image_filename"),
+  createdAt: integer("created_at", { mode: "timestamp" })
+    .notNull()
+    .$defaultFn(() => new Date()),
+  updatedAt: integer("updated_at", { mode: "timestamp" })
+    .notNull()
+    .$defaultFn(() => new Date()),
+});
+
 export const settings = sqliteTable("settings", {
   key: text("key").primaryKey(),
   value: text("value").notNull(),