feat(09-01): add classification column to setupItems with service layer and tests

- Add classification text column (default 'base') to setupItems schema
- Add classificationSchema and updateClassificationSchema Zod validators
- Add UpdateClassification type inferred from Zod schema
- Implement updateItemClassification service function
- Modify getSetupWithItems to return classification field
- Modify syncSetupItems to preserve classifications across re-sync
- Add tests for classification CRUD, preservation, and cross-setup independence
- Generate and apply Drizzle migration

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

src/shared/types.ts

@@ -17,6 +17,7 @@ import type {
 	syncSetupItemsSchema,
 	updateCandidateSchema,
 	updateCategorySchema,
+	updateClassificationSchema,
 	updateItemSchema,
 	updateSetupSchema,
 	updateThreadSchema,
@@ -37,6 +38,7 @@ export type ResolveThread = z.infer<typeof resolveThreadSchema>;
 export type CreateSetup = z.infer<typeof createSetupSchema>;
 export type UpdateSetup = z.infer<typeof updateSetupSchema>;
 export type SyncSetupItems = z.infer<typeof syncSetupItemsSchema>;
+export type UpdateClassification = z.infer<typeof updateClassificationSchema>;
 
 // Types inferred from Drizzle schema
 export type Item = typeof items.$inferSelect;