fix(agent): abort generate_app_icon on cancel so the chat never hangs

feat(agent): generate_app_icon tool (Reachy sticker) with chat preview

feat(preview): seed HF token so preview runs the real host (mountHost)

fix(auto-fix): drop stale missing-asset race + wire the booted gate

test(frontend): add Vitest/Playwright harness + regression tests (RED)

feat(autofix): self-correcting TS loop with esbuild-wasm and diagnostics panel