Phase 5: Alembic baseline, per-site deploy, ADRs to docs/adr

Migration runner ready and a sister site can deploy from a clean
checkout with one .env file.

ADRs relocated (migrations/adr/ -> docs/adr/):
- migrations/ is now Alembic territory, not docs.
- All cross-references updated: CLAUDE.md, docs/PLUGIN-HOOKS.md,
  docs/PLUGIN-QUICKSTART.md.

Alembic initialized (migrations/):
- env.py, script.py.mako, alembic.ini copied from Flask-Migrate
  templates so `flask db migrate` and `flask db upgrade` work without
  a one-time `flask db init` (which would clash with the existing
  migrations/ directory).
- Baseline migration generated via autogenerate, captures all 47
  tables (core models + 6 plugins) as the upgrade target. Ready for
  per-site `flask db upgrade` from an empty schema.

Deploy artifacts:
- Dockerfile: python:3.12-slim base, gunicorn server, non-root user,
  healthcheck against /api/auth/login. Single image bundles all six
  plugins; sites enable via `flask plugin install <name>`.
- docker-compose.yml: MySQL 8 + API container, healthcheck-gated
  startup, env-driven secrets that fail loud on missing values
  (`${SECRET_KEY:?}` form).
- .env.example: full env-var inventory with comments. Calls out
  required vs optional. Matches what ProductionConfig.validate
  enforces.

docs/DEPLOY.md:
- Step-by-step per-site runbook: clone, configure .env, bring up
  stack, run migrations, seed reference data, install plugins,
  create admin, front with TLS, backups, updates.
- Common-issues table.
- Cross-links to ADR-004 (per-site rationale), ADR-003 (plugin
  distribution), and the config source.

Skills:
- migrating-asset-schema: Alembic + one-shot data migration policy.
  Rules: additive first, renames are three steps, destructive ops
  need rollback, equipment migration filter per ADR-001 + ADR-005.
- hardening-flask-config: production validation, CORS allowlist
  policy, JWT cookie hardening, per-site deploy isolation per ADR-004.

CLAUDE.md updated to reflect the post-Phase-5 state. No tests added
this commit; the Alembic baseline is exercised by the existing
db.create_all-based test suite (tests do not touch the migration
runner; that's by design until per-plugin migrations land).

Test count unchanged: 101 passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/PLUGIN-HOOKS.md

@@ -2,7 +2,7 @@
 
 This is the canonical reference for the shopdb-flask plugin contract. Plugin authors implement `BasePlugin` and override the hooks they care about. Hooks marked `required` must be implemented; hooks marked `optional` have sensible defaults and can be left alone.
 
-The contract is locked in [ADR-001](../migrations/adr/ADR-001-asset-as-platform-contract.md) and versioned per [ADR-002](../migrations/adr/ADR-002-plugin-versioning.md).
+The contract is locked in [ADR-001](../docs/adr/ADR-001-asset-as-platform-contract.md) and versioned per [ADR-002](../docs/adr/ADR-002-plugin-versioning.md).
 
 ## Contract version
 
@@ -202,7 +202,7 @@ class ComputersPlugin(BasePlugin):
 
 ### `get_collector_schema() -> Optional[Dict]`
 
-Declares the JSON Schema for an external collector pushing to `/api/collector/<pluginname>`. See [ADR-006](../migrations/adr/ADR-006-collector-contract.md) for the contract.
+Declares the JSON Schema for an external collector pushing to `/api/collector/<pluginname>`. See [ADR-006](../docs/adr/ADR-006-collector-contract.md) for the contract.
 
 ```python
 class ComputersPlugin(BasePlugin):
@@ -272,7 +272,7 @@ position = resolve_asset_position(asset)
 # Returns dict: {'mapx': 234, 'mapy': 567, 'positionsource': 'self' | 'related' | 'location' | None}
 ```
 
-See [ADR-001](../migrations/adr/ADR-001-asset-as-platform-contract.md) for the position resolution algorithm.
+See [ADR-001](../docs/adr/ADR-001-asset-as-platform-contract.md) for the position resolution algorithm.
 
 ## Removed hooks
 
@@ -286,8 +286,8 @@ The following hooks existed in early drafts and have been removed for v1:
 
 When you change anything documented here, you must:
 
-1. Bump `__contract_version__` per [ADR-002](../migrations/adr/ADR-002-plugin-versioning.md): major for removals or signature changes, minor for additive optional hooks, patch for docs.
-2. Update [ADR-001](../migrations/adr/ADR-001-asset-as-platform-contract.md) if the contract surface itself changed (or supersede with a new ADR).
+1. Bump `__contract_version__` per [ADR-002](../docs/adr/ADR-002-plugin-versioning.md): major for removals or signature changes, minor for additive optional hooks, patch for docs.
+2. Update [ADR-001](../docs/adr/ADR-001-asset-as-platform-contract.md) if the contract surface itself changed (or supersede with a new ADR).
 3. Add or update the test in `tests/test_plugin_contract.py` that asserts the new behavior.
 
 The skill `defining-asset-contract` walks through the full checklist.