feat: add HA infrastructure, CI/CD pipeline, and Redis/Celery hardening

- Add docker-compose.ha.yml for PostgreSQL/Redis HA setup with Patroni and Sentinel
- Add docker-compose.prod.yml for production deployment
- Add GitHub Actions CI/CD workflow (build.yml)
- Add install.cmd for Windows one-click setup
- Harden Redis connection with retry logic and health checks
- Add Celery HA config with Redis Sentinel support
- Add HA operations runbook
- Update README with deployment and architecture docs
- Move landing page spec to .claude/specs/design/
- Update memory intelligence PRD

backend/app/core/celery_app.py

@@ -5,11 +5,33 @@ from celery.schedules import crontab
 
 from app.core.config import settings
 
-celery_app = Celery(
-    "dreamweaver",
-    broker=settings.celery_broker_url,
-    backend=settings.celery_result_backend,
-)
+if settings.redis_sentinel_enabled and settings.redis_sentinel_urls:
+    sentinel_broker = ";".join(settings.redis_sentinel_urls)
+    celery_app = Celery(
+        "dreamweaver",
+        broker=sentinel_broker,
+        backend=sentinel_broker,
+    )
+    celery_app.conf.broker_transport_options = {
+        "master_name": settings.redis_sentinel_master_name,
+        "sentinel_kwargs": {
+            "password": settings.redis_sentinel_password or None,
+            "socket_timeout": settings.redis_sentinel_socket_timeout,
+        },
+    }
+    celery_app.conf.result_backend_transport_options = {
+        "master_name": settings.redis_sentinel_master_name,
+        "sentinel_kwargs": {
+            "password": settings.redis_sentinel_password or None,
+            "socket_timeout": settings.redis_sentinel_socket_timeout,
+        },
+    }
+else:
+    celery_app = Celery(
+        "dreamweaver",
+        broker=settings.celery_broker_url,
+        backend=settings.celery_result_backend,
+    )
 
 celery_app.conf.update(
     task_track_started=True,