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>

docker-compose.yml

@@ -0,0 +1,19 @@
+services:
+  gateway:
+    build: .
+    ports:
+      - "8000:8000"
+    environment:
+      # Set a strong random value in production — signs the admin session cookies.
+      GATEWAY_SECRET_KEY: change-me-in-production
+      GATEWAY_ADMIN_USER: admin
+      GATEWAY_ADMIN_PASSWORD: admin
+      # Retention (days; 0 = keep forever)
+      GATEWAY_PAYLOAD_RETENTION_DAYS: "7"
+      GATEWAY_LOG_RETENTION_DAYS: "90"
+    volumes:
+      - gateway-data:/data
+    restart: unless-stopped
+
+volumes:
+  gateway-data: