feat(10-01): add pros/cons columns through backend

- Add pros/cons nullable TEXT columns to threadCandidates schema
- Generate and apply Drizzle migration (0004_soft_synch.sql)
- Mirror pros/cons columns in test helper CREATE TABLE
- createCandidate: pass pros/cons to values() object
- updateCandidate: add pros/cons to Partial type
- getThreadWithCandidates: include pros/cons in select projection
- createCandidateSchema: add optional pros/cons string fields

src/db/schema.ts

@@ -59,6 +59,8 @@ export const threadCandidates = sqliteTable("thread_candidates", {
 	productUrl: text("product_url"),
 	imageFilename: text("image_filename"),
 	status: text("status").notNull().default("researching"),
+	pros: text("pros"),
+	cons: text("cons"),
 	createdAt: integer("created_at", { mode: "timestamp" })
 		.notNull()
 		.$defaultFn(() => new Date()),