Add sandbox manager, multi-layer throttle, monitoring, external testing, cyberpunk UI

fix: use OAUTH_REDIRECT_URI directly in both login and callback

fix: add missing httpx import in app.py (caused NameError in OAuth callback)

feat: OAuth-only login, removed manual token entry UI

fix: OAuth button returns 200 + configured:false instead of 400, smooth fallback to token entry

feat: persistent sessions, HF OAuth login, auto-key-load from vault, logout

feat: wire 75% compression, DAG cycle/priority, resource mgmt, enriched prompts, fallbacks