chore(planning): update config.json and remove stale debug artifact

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

.planning/config.json

@@ -9,6 +9,7 @@
     "plan_check": true,
     "verifier": true,
     "nyquist_validation": true,
+    "use_worktrees": true,
     "auto_advance": false,
     "test_gate": true,
     "security_check": true,

.planning/debug/phase-12-cloud-schema-cold-start.md

@@ -1,49 +0,0 @@
-# Debug: Phase 12 Cloud Schema Cold Start
-
-**Status:** root cause found
-**Date:** 2026-06-19
-**UAT tests:** 1, 2
-
-## Symptoms
-
-- `GET /api/cloud/connections` raises `psycopg.errors.UndefinedColumn` for `cloud_connections.display_name_override`.
-- `POST /api/cloud/connections/webdav` reaches `_upsert_cloud_connection` and raises the same error, preventing Nextcloud account connection.
-
-## Root Cause
-
-The running application code and ORM are at Phase 12, but the live PostgreSQL schema remains at Alembic revision `0005`.
-
-Live evidence:
-
-```text
-$ docker compose run --rm backend alembic current
-0005
-```
-
-Migration `backend/migrations/versions/0006_cloud_resource_foundation.py` correctly adds `cloud_connections.display_name_override` and the Phase 12 cloud metadata tables. The ORM correctly maps that column. The defect is that `docker-compose.yml` has no migration service and the backend command starts Uvicorn directly. Backend, Celery worker, and Celery beat depend on PostgreSQL health, but none depends on `alembic upgrade head` completing. Therefore `docker compose up` can run new application code against an old persistent database.
-
-## Why Automated Tests Missed It
-
-- Most backend tests build schema directly from `Base.metadata.create_all`, which validates the final ORM shape but bypasses Alembic history and deployment ordering.
-- Existing Alembic tests target early migrations and do not exercise an existing PostgreSQL database upgraded from `0005` to `head`.
-- Phase verification checked migration file structure and model parity, not a real cold-start Compose upgrade path.
-
-## Files Involved
-
-- `docker-compose.yml` — no one-shot migration service; backend/workers start after DB health only.
-- `backend/migrations/versions/0006_cloud_resource_foundation.py` — contains the required column and tables but was not applied.
-- `backend/db/models.py` — queries `display_name_override`, exposing schema drift immediately.
-- `backend/tests/test_alembic.py` — lacks a 0005-to-head PostgreSQL upgrade regression.
-- `.planning/phases/12-cloud-resource-foundation/12-VALIDATION.md` — cold-start test expected migration completion, but execution evidence did not actually verify Compose migration orchestration.
-
-## Required Fix Direction
-
-1. Add a one-shot Compose migration service that runs `alembic upgrade head` with `DATABASE_MIGRATE_URL` after PostgreSQL becomes healthy.
-2. Make backend, Celery worker, and Celery beat wait for that migration service to complete successfully.
-3. Add a PostgreSQL/Compose regression proving an existing revision `0005` advances to `0006/head` before the API starts, and assert `display_name_override`, `cloud_items`, `cloud_item_topics`, and `cloud_folder_states` exist.
-4. Document the migration lifecycle and recovery command in README/RUNBOOK.
-5. For the currently running environment, apply `alembic upgrade head` and restart application processes before resuming UAT.
-
-## Scope
-
-Both UAT blockers share this root cause. No evidence currently indicates a separate Nextcloud credential or WebDAV defect.