Add OpenClaw unwrap flow and non-blocking proxy startup

fix(openclaw): wait for proxy before gateway routing

fix(openclaw): keep gateway routing runtime-only

fix(openclaw): route codex through headroom proxy

Auto-detect proxyUrl by default and keep explicit override

Harden openclaw plugin proxy handling and metadata

OpenClaw plugin fixes, telemetry fix, cost tracker improvement, tokenBudget support

feat: add OpenClaw ContextEngine plugin (@headroom-ai/openclaw)