Add GACCode quick access and improve OpenClaw feedback

[cwj526]

Summary

• add GACCode quick access flow with paired gac-claude and gac-codex provider setup
• improve model test/startup handling with timeouts, gateway mode bootstrap, and clearer UI error feedback
• include remaining local repo changes now present on the branch

Verification

• npm run build
• cargo test --manifest-path src-tauri/Cargo.toml -- --nocapture