Make update notice download-ready (codex)

[numnx]

🧩 Task: Make update notice download-ready

Automated task PR opened by Code UX for T02.

📋 Summary

Sprint: Sprint 156 · Chat Status widget + Update downloadlink · Task: T02

Connect the chat rich status widget to live sprint/task progress and make update notices open the correct official npm or Electron release download in the user’s browser.

📝 Full Task Prompt

## Objective
Update the Electron title-bar notice so clicking `Update available` opens the correct official download target in the user’s default browser, with a clear download icon and accessible labeling.

## Scope
- `dashboard/src/v2/components/TitleBar.tsx`
- `dashboard/src/v2/components/__tests__/TitleBar.test.tsx`
- `src/electron/main.ts`
- `src/electron/dashboard-network-policy.ts`
- `tests/backend/electron/dashboard-network-policy.test.ts`
- `docs/deployment/electron-desktop.md`
- `docs-web/user/installation.md`
- `docs-web/content/docs/user-installation.mdx`
- Consumes the `downloadTargets` contract added by T01.

## Implementation Requirements
1. Replace the title-bar update badge’s external-link icon with the appropriate lucide download icon and update the copy/accessible name so users understand it opens the release download page.
2. Choose the Electron download target when `window.codeUxDesktop` is present and choose the npm target for non-Electron dashboard sessions; fall back to the existing `releaseUrl` only if the new target is absent.
3. Keep the link `target="_blank"`/safe rel behavior so Electron routes it through `setWindowOpenHandler` and `shell.openExternal` instead of navigating inside the app.
4. Add or update tests proving the Electron environment uses the Electron target, browser mode uses the npm target, failed checks render no action, and the rendered control includes the download icon/accessibility label.
5. Add or update Electron navigation-policy coverage if needed to prove official `https` release/npm URLs are classified as external and unsafe schemes remain denied.
6. Update desktop and public installation docs to describe the clickable update notice and its browser-opening behavior.

## Constraints
- Do not make the title bar appear in browser mode if existing behavior hides it outside Electron; only ensure the target selection logic supports browser consumers safely.
- Do not use `window.open` manually in the renderer; rely on the anchor and Electron’s existing external navigation policy.
- Preserve no-drag behavior, compact title-bar height, keyboard focus visibility, and existing update-check polling cadence.
- Do not hardcode a specific current package version in the component.

## Verification
- Run `pnpm run test:dashboard -- dashboard/src/v2/components/__tests__/TitleBar.test.tsx`.
- Run `pnpm run test:backend -- tests/backend/electron/dashboard-network-policy.test.ts` if navigation-policy coverage changes.
- Run `pnpm run lint`.
- Success means the update notice is clickable, uses a download icon, selects the correct target, and Electron opens the URL externally.

✅ QA Review

⏳ QA review runs after this PR is opened. Check the task card in the dashboard for the outcome once it lands.

🤖 Model & Provider

Provider	Codex CLI
Model	gpt-5.5

⏱️ Timing

Started	2026-07-07 04:28:19 UTC
Finished	2026-07-07 04:34:41 UTC
Duration	6m 22s

📊 Token Usage

Metric	Value
Input tokens	168,637
Cached input tokens	1,778,304
Output tokens	11,755
Total tokens	1,958,696
Invocations	1
Tool calls	47
Active time	5m 52s

Included usage estimate (subscription/local login): $2.08

🌿 Branch Info

Base: feature/CODUX-156-chat-status-widget-update-downloadlink
Head: task/feature-codux-156-chat-status-widget-update-down-t02-codex-mra5f6av

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🤖 Generated by Code UX