Add CRM stub flag, deploy/backup scripts, CI and prod runbook

- CRM_USE_STUB: local runs no longer reach the live CRM. With only the
  Checkbox stub, a stub receipt would still move the real order to PACKED.
  Refused in production, same as CHECKBOX_USE_STUB.
- scripts/deploy.sh: backup, fast-forward main, build, health check and
  code rollback on failure. scripts/backup.sh: pg_dump with verification
  and 14-day rotation (used by cron and deploy.sh).
- Gitea Actions CI: ruff + pytest, oxlint + build.
- DEPLOY.md runbook; CLAUDE.md rules for safe local development.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -0,0 +1,37 @@
+# Проверки на каждый PR и push в main. Нужен зарегистрированный act_runner (см. DEPLOY.md).
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  backend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: backend
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - run: pip install -e ".[dev]"
+      - run: ruff check app tests
+      # SECRET_KEY/ENCRYPTION_KEY подставляет tests/conftest.py.
+      - run: pytest -q
+
+  frontend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: frontend
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run build