feat: extract headless daemon host bootstrap

[parsakhaz]

Summary

• extract the daemon-owned service/runtime bootstrap into a reusable createPaneDaemonHost() host object
• add a dedicated headless daemon entrypoint and runnable scripts for booting Pane without a BrowserWindow
• remove remaining index.ts bootstrap assumptions from task queue, resource monitor, app-directory parsing, and panel webview context wiring

What changed

• added main/src/daemon/bootstrap.ts to own service initialization, local daemon startup, runtime sink installation, and shared shutdown
• added main/src/daemon/headless.ts as the first headless Electron entrypoint for self-hosted daemon mode
• updated main/src/index.ts so desktop mode uses the extracted host instead of duplicating service startup
• made TaskQueue choose its local in-process queue without depending on process.versions.electron
• made ResourceMonitorService accept injected session/app dependencies instead of requiring ../index
• made app-directory resolution safe to use outside the desktop entrypoint and added CLI parsing helpers/tests
• routed panel webview registration through the runtime webview-context accessor instead of importing ../index

Validation

• pnpm typecheck
• pnpm lint (passes with existing repo warnings)
• CI=1 pnpm --filter main test -- --run
• pnpm run build:main
• PANE_DIR=/tmp/pane-phase3-remote-smoke-final xvfb-run -a pnpm test:ci
• manual headless smoke: booted main/dist/main/src/daemon/headless.js without creating a BrowserWindow, confirmed the local daemon socket was announced, and confirmed clean external SIGTERM exit

Review note

• terminal Ctrl+C against the Electron wrapper is still noisy in local shell smoke, but an external SIGTERM to the Electron process exits cleanly after shutdown. I treated external signal stop as the meaningful daemon validation path for this slice.

[parsakhaz]

@codex review

[parsakhaz]

@claude review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".