Initial commit: clean project structure

- Backend: FastAPI + SQLAlchemy + Celery (Python 3.11+)
- Frontend: Vue 3 + TypeScript + Pinia + Tailwind
- Admin Frontend: separate Vue 3 app for management
- Docker Compose: 9 services orchestration
- Specs: design prototypes, memory system PRD, product roadmap

Cleanup performed:
- Removed temporary debug scripts from backend root
- Removed deprecated admin_app.py (embedded UI)
- Removed duplicate docs from admin-frontend
- Updated .gitignore for Vite cache and egg-info

backend/app/core/celery_app.py

@@ -0,0 +1,33 @@
+"""Celery application setup."""
+
+from celery import Celery
+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,
+)
+
+celery_app.conf.update(
+    task_track_started=True,
+    task_serializer="json",
+    accept_content=["json"],
+    result_serializer="json",
+    timezone="Asia/Shanghai",
+    enable_utc=True,
+    beat_schedule={
+        "check_push_notifications": {
+            "task": "app.tasks.push_notifications.check_push_notifications",
+            "schedule": crontab(minute="*/15"),
+        },
+        "prune_expired_memories": {
+            "task": "app.tasks.memory.prune_memories_task",
+            "schedule": crontab(minute="0", hour="3"),  # Daily at 03:00
+        },
+    },
+)
+
+celery_app.autodiscover_tasks(["app.tasks"])