chore(e2e): review screenshots for #2404

[copse-release-bot]

Screenshot candidates rendered for parent PR
#2404 at
2c1eb06c756b3d68c1f6458118d18b4310b4e307 by
CI run 34157525663.

Review GitHub's image diffs, then merge this PR (or enable auto-merge) to apply the
accepted references to claude/copse-threads-prototype-c5c83c. This branch contains
only PNG candidates from the immutable
reference-screenshot-candidates-34157525663 artifact and never targets main.

If the parent branch has advanced beyond the source SHA above, do not merge this PR;
the successful CI run for the new head will replace it.

[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
• 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.}