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/services/fetchers/__init__.py

@@ -0,0 +1,12 @@
+"""Fetcher implementations."""
+from app.services.fetchers.base import BaseFetcher, FetchedItem
+from app.services.fetchers.rss import RSSFetcher
+
+__all__ = ["BaseFetcher", "FetchedItem", "RSSFetcher"]
+
+
+def get_fetcher(kind: str, **kwargs) -> BaseFetcher:
+    if kind == "rss":
+        return RSSFetcher(**kwargs)
+    # html_list / tg_channel: Phase 2 实现,这里抛错
+    raise NotImplementedError(f"fetcher not implemented for kind={kind}")