Initial commit: API gateway with admin console

- FastAPI async gateway with httpx proxying to multiple upstreams
- SQLite database with SQLAlchemy ORM
- Admin console: manage services, users, API keys, endpoint access
- Per-key, per-endpoint granular access control
- OpenAPI document sync and caching (5-minute TTL)
- Request/response logging with full transaction inspection
- In-memory rate limiting (per-key, fixed-window)
- Tiered log retention (7d payloads, 90d rows, incremental vacuum)
- TLS verification toggle per service (for self-signed certificates)
- Service connectivity validation with automatic endpoint refresh
- Request browser with filters and deep-link inspection
- Docker setup with persistent volume
- Modal forms for create/edit flows

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

app/database.py

@@ -0,0 +1,22 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, sessionmaker
+
+from app import config
+
+engine = create_engine(
+    config.DATABASE_URL,
+    connect_args={"check_same_thread": False} if config.DATABASE_URL.startswith("sqlite") else {},
+)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()