feat: Update Docker and Kubernetes for database infrastructure

- Update backend Dockerfile with PostgreSQL deps and entrypoint
- Add entrypoint.sh with db/redis wait and auto-migration
- Add /ready endpoint for Kubernetes readiness probe
- Enhance /health endpoint with database and Redis status
- Update k8s deployment with PostgreSQL and Redis services
- Add proper secrets management for database credentials
- Update k8s readiness probe to use /ready endpoint

main.py

@@ -305,11 +305,36 @@ async def health_check():
     health_status = await health_checker.check_health()
     status_code = 200 if health_status.get("status") == "healthy" else 503
     
+    # Check database connection
+    db_status = {"status": "not_configured"}
+    try:
+        from database.connection import check_db_connection
+        if check_db_connection():
+            db_status = {"status": "healthy"}
+        else:
+            db_status = {"status": "unhealthy"}
+    except Exception as e:
+        db_status = {"status": "error", "error": str(e)}
+    
+    # Check Redis connection
+    redis_status = {"status": "not_configured"}
+    redis_client = get_redis_client()
+    if redis_client:
+        try:
+            redis_client.ping()
+            redis_status = {"status": "healthy"}
+        except Exception as e:
+            redis_status = {"status": "unhealthy", "error": str(e)}
+    elif redis_client is False:
+        redis_status = {"status": "connection_failed"}
+    
     return JSONResponse(
         status_code=status_code,
         content={
             "status": health_status.get("status", "unknown"),
             "translation_service": config.TRANSLATION_SERVICE,
+            "database": db_status,
+            "redis": redis_status,
             "memory": health_status.get("memory", {}),
             "disk": health_status.get("disk", {}),
             "cleanup_service": health_status.get("cleanup_service", {}),
@@ -322,6 +347,42 @@ async def health_check():
     )
 
 
+@app.get("/ready")
+async def readiness_check():
+    """Kubernetes readiness probe - check if app can serve traffic"""
+    issues = []
+    
+    # Check database
+    try:
+        from database.connection import check_db_connection, DATABASE_URL
+        if DATABASE_URL:  # Only check if configured
+            if not check_db_connection():
+                issues.append("database_unavailable")
+    except ImportError:
+        pass  # Database module not available - OK for development
+    except Exception as e:
+        issues.append(f"database_error: {str(e)}")
+    
+    # Check Redis (optional but log if configured and unavailable)
+    if REDIS_URL:
+        redis_client = get_redis_client()
+        if redis_client:
+            try:
+                redis_client.ping()
+            except Exception:
+                issues.append("redis_unavailable")
+        elif redis_client is False:
+            issues.append("redis_connection_failed")
+    
+    if issues:
+        return JSONResponse(
+            status_code=503,
+            content={"ready": False, "issues": issues}
+        )
+    
+    return {"ready": True}
+
+
 @app.get("/languages")
 async def get_supported_languages():
     """Get list of supported language codes"""