feat(delivery): live CI/CD pipeline + demo runtime (v2 phase A3-3)

A push to `dev` now becomes a live demo, and a failed build never takes the
demo down.

- Four tables (pipeline_runs, pipeline_steps, releases, app_runtimes) and their
  migration; alembic upgrade/downgrade/check all clean.
- DeliveryService implements DeliveryHooks: on_app_created provisions the demo
  port + host + first build (idempotently); on_branch_pushed queues a run for
  `dev` and supersedes older *queued* runs, leaving a running one alone.
- The 8-step pipeline. Blue/green is real: the replacement starts on a staging
  port, is healthchecked, and only then does the route move — then the previous
  container is stopped. A failure removes the replacement, releases its port and
  leaves the old container serving.
- The demo port ledger is the DATABASE, not the router adapters' in-memory maps:
  the API and the delivery worker are separate processes.
- Runs are claimed with a conditional UPDATE, so two workers never build the
  same run.
- Live logs are batched (1 event / 500 ms, 200 lines) and redacted as a whole
  tail — per-chunk redaction misses a secret split across pipe reads, and the
  *stored* tail leaked until this was fixed.
- delivery worker: drain the queue, then poll remotes for pushes made outside
  the engine.
- 7 routes; reads need membership, actions need projects.manage and are audited.

Tests: 415 API (+21, 1 docker-marked skipped); ruff, mypy, alembic check clean.

Report: docs/plan/reports/agent-3-phase-3.md

apps/api/app/application/container.py

@@ -17,6 +17,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.application.container_delivery import (
     build_delivery_hooks,
+    build_delivery_service,
     build_deploy_target_tester,
     build_repo_workspace,
 )
@@ -166,6 +167,7 @@ def build_sandbox_service(session: AsyncSession) -> SandboxService:
 __all__ = [
     "build_billing_service",
     "build_delivery_hooks",
+    "build_delivery_service",
     "build_deploy_target_tester",
     "build_memory",
     "build_model_grants",