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>

backend/tests/test_crm_client_factory.py

@@ -0,0 +1,37 @@
+"""Выбор реализации CRM-клиента по `CRM_USE_STUB`."""
+
+from __future__ import annotations
+
+from collections.abc import Iterator
+
+import pytest
+
+from app.core.config import settings
+from app.services.crm.client import get_crm_client
+from app.services.crm.exo_client import ExoCrmClient
+from app.services.crm.stub_client import StubCrmClient
+
+
+@pytest.fixture(autouse=True)
+def _fresh_factory() -> Iterator[None]:
+    get_crm_client.cache_clear()
+    yield
+    get_crm_client.cache_clear()
+
+
+def test_real_client_by_default(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(settings, "crm_use_stub", False)
+    assert isinstance(get_crm_client(), ExoCrmClient)
+
+
+def test_stub_when_enabled(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(settings, "crm_use_stub", True)
+    monkeypatch.setattr(settings, "environment", "local")
+    assert isinstance(get_crm_client(), StubCrmClient)
+
+
+def test_stub_forbidden_in_production(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(settings, "crm_use_stub", True)
+    monkeypatch.setattr(settings, "environment", "production")
+    with pytest.raises(RuntimeError, match="CRM_USE_STUB"):
+        get_crm_client()