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>

tests/helpers/db.ts

@@ -73,7 +73,8 @@ export function createTestDb() {
     CREATE TABLE setup_items (
       id INTEGER PRIMARY KEY AUTOINCREMENT,
       setup_id INTEGER NOT NULL REFERENCES setups(id) ON DELETE CASCADE,
-      item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE
+      item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+      classification TEXT NOT NULL DEFAULT 'base'
     )
   `);