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/shared/schemas.ts

@@ -53,6 +53,8 @@ export const createCandidateSchema = z.object({
 	productUrl: z.string().url().optional().or(z.literal("")),
 	imageFilename: z.string().optional(),
 	status: candidateStatusSchema.optional(),
+	pros: z.string().optional(),
+	cons: z.string().optional(),
 });
 
 export const updateCandidateSchema = createCandidateSchema.partial();