feat(api): A3 backend skeleton with FastAPI + SQLModel

- 3 tables: Meeting / TranscriptSegment / Summary (with state machine)
- Routes: /api/upload-url + /api/upload-complete + meetings CRUD
- MinIO presigned PUT for direct browser upload
- BackgroundTasks state-machine stub for A5 to flesh out
- SQLite for local dev, PostgreSQL+asyncpg for prod
- CORS configured for frontend on 4490

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/main.py

@@ -0,0 +1,31 @@
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from .config import settings
+from .db import init_db
+from .routers import meetings as meetings_router
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    await init_db()
+    yield
+
+
+app = FastAPI(title="MeetNote API", version="0.1.0", lifespan=lifespan)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=settings.cors_origins_list,
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(meetings_router.router)
+
+
+@app.get("/health")
+async def health():
+    return {"ok": True, "service": "meetnote-api", "version": "0.1.0"}