feat: initial MVP - FastAPI backend + Vue3 frontend + docker-compose

- backend: FastAPI + SQLAlchemy 2.0(async) + asyncpg + Alembic
- 7 API routes: auth/me/articles/sources/bookmarks/subscriptions/admin
- models: User/Source/Article/Bookmark/Subscription/ApiToken
- services: RSS fetcher (feedparser) + Tencent TMT translator with quota + cache + local NLLB fallback
- workers: APScheduler + asyncio pipeline (fetch -> dedupe -> insert -> translate)
- seed scripts: create_user, seed_sources (5 RSS: Reuters/BBC/Al Jazeera/NHK/DW)
- frontend: Vue 3 + Vite + Naive UI + Pinia + vue-router
- pages: Login, Feed (24h), ArticleDetail, Sources, Bookmarks, AdminSources
- deploy: docker-compose (postgres/redis/api/worker/frontend/caddy)
- docs: README, DEPLOY, architecture, acceptance

backend/app/redis_client.py

@@ -0,0 +1,31 @@
+"""Redis 客户端(单例)。用于:
+- 翻译缓存
+- 翻译字符配额(月度)
+- 限流(后续)
+"""
+from __future__ import annotations
+
+import redis.asyncio as redis_async
+
+from app.config import settings
+
+_pool: redis_async.Redis | None = None
+
+
+def get_redis() -> redis_async.Redis:
+    global _pool
+    if _pool is None:
+        _pool = redis_async.from_url(
+            settings.redis_url,
+            encoding="utf-8",
+            decode_responses=True,
+            max_connections=20,
+        )
+    return _pool
+
+
+async def close_redis() -> None:
+    global _pool
+    if _pool is not None:
+        await _pool.aclose()
+        _pool = None