feat(WP-0004): railiance deployment & service ops

- Dockerfile (multi-stage, uv-based, slim runtime)
- .dockerignore
- docker-compose.railiance.yml (Temporal + NATS + PG, no Elasticsearch)
- GET /health endpoint (db + temporal probes, 200/503)
- .env.example (complete env var reference)
- Makefile: migrate, sync-all, dev-up/down, railiance-up/down,
  start-worker, start-api, start-event-router, help targets;
  extracted sync-event-types Python to scripts/sync_event_types.py
- SIGTERM graceful shutdown in worker.py and event_router.py
- docs/runbook.md: Railiance deployment section

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

src/activity_core/api.py

@@ -30,8 +30,9 @@ from datetime import datetime, timezone
 from typing import Any
 
 from fastapi import FastAPI, HTTPException
+from fastapi.responses import JSONResponse
 from pydantic import BaseModel
-from sqlalchemy import select
+from sqlalchemy import select, text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from temporalio.client import Client
 
@@ -275,6 +276,32 @@ async def trigger_definition(definition_id: uuid.UUID) -> dict[str, str]:
 
 # T42: Curator gate — event type approval endpoint
 
+@app.get("/health")
+async def health() -> JSONResponse:
+    db_ok = False
+    temporal_ok = False
+
+    try:
+        async with _get_db()() as session:
+            await session.execute(text("SELECT 1"))
+        db_ok = True
+    except Exception:
+        pass
+
+    try:
+        await _get_temporal().describe_namespace(TEMPORAL_NAMESPACE)
+        temporal_ok = True
+    except Exception:
+        pass
+
+    status = "ok" if db_ok and temporal_ok else "degraded"
+    code = 200 if status == "ok" else 503
+    return JSONResponse(
+        {"status": status, "db": db_ok, "temporal": temporal_ok},
+        status_code=code,
+    )
+
+
 @app.post("/event-types/{type_id}/approve", status_code=200)
 async def approve_event_type(type_id: str) -> dict[str, str]:
     """Approve a pending event type, setting its status to 'active'.