Show images in proposed changes

[jonathanKingston]

Summary

• render proposed image changes as before and after previews instead of binary text
• preserve raster bytes across staging, approval, delete, and rename flows
• add focused unit, renderer, and Electron visual coverage

Testing

• pnpm run typecheck
• pnpm run build
• pnpm test -- diff-queue local-workspace-fs image-path git-changes-pane-proposed-fetch
• pnpm run test:e2e -- --spec tests/e2e/git-changes-image.e2e.ts
• pnpm run check:e2e-syntax
• pnpm run check: static gates passed; the broad unit phase cannot complete in the managed sandbox because loopback-listener tests fail with EPERM and leave network-sensitive workers running

Visual evidence

The focused Electron spec updates tests/e2e/screenshots/git-changes-image-proposed.png with the proposed before and after preview plus approval controls.

[copse-release-bot]

Reference screenshots ready for review

Review GitHub’s image diffs in screenshot PR #2638.
Merge it (or enable auto-merge) to apply the accepted PNGs to codex/proposed-image-previews.

Rendered for c1802fedaa82 by CI run 34390166541; the immutable artifact is reference-screenshot-candidates-34390166541.

If this source branch moves, a later successful render closes the stale review PR and replaces this link.

[github-actions]

🖥️ PR preview

• Marketing site
• Browser demo
  Interactive, with a mocked backend — jump to a scenario:
• Builds a cupcake site
• Agent-proposed edits open the Changes panel
• Markdown list indentation
• Unattended container run
• Responsive composer footer
• Subagent display visual reference
• Subagent stays ungrouped beside reading tools
• Semantic search subagent markdown
• Light-theme approval with a bright accent
• Light-theme syntax, fills, and selection
• Grouped outside-sandbox command approval
• Remote desktop discovered-port list with one selected
• Settings scroll + sticky footer geometry
• Per-model reasoning / temperature / top-p
• Thread switch hydration notice
• Thread switch hydration failure
• Chat layout styling
  _{Static demo of the renderer against a mock API — the browser pane, terminal, and all main-process IPC are stubbed, so it never proves main-process behaviour. Rebuilt whenever a push changes the demo bundle; these links go live once the queued deploy lands, shortly after this comment. Removed when the PR closes.}