[Feat] Show visual proof images inline in the task transcript

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

Internal product request from Slack (no GitHub issue): show captured visual proof inline in the web task transcript next to the capture/upload step.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Successful manage_artifacts uploads with artifactType: "visual-proof" now render an always-visible, image-only preview under that tool row in the web task transcript.

• Previews are capped at 100px tall in chat
• Clicking the image opens the in-app Artifacts detail view for that artifact (path/version from session or upload viewUrl)
• Chat chrome is the clickable image only (no external open fallback, no link/download row)

Why this change was made

Visual proof already landed in the Artifacts panel, but the center transcript only showed the tool steps as text. Reviewers wanted the screenshot itself next to the capture/upload step so the stream is self-explanatory, with a compact in-chat treatment that deep-links to the artifact detail surface.

Impact

Users reviewing a task on the web see compact visual-proof images inline under the matching upload tool result and can open the full artifact detail from that thumbnail. Artifacts panel behavior stays the same. Non-proof uploads and ordinary tools are unchanged.

How it was tested

• Vitest unit/component coverage for visual-proof extraction, thumbnail vs rawUrl preference, path parsing from viewUrl, always-visible preview rendering, and click-through to artifact detail: 23 passed
• Pre-push lint:fast, check-types:fast, and knip passed for the branch
• Live browser screenshot for this preview remains blocked in this sandbox (no transcript with a visual-proof upload tool result)

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

No new code issues found. See task

• apps/web/src/app/(sandbox)/task/[taskId]/messages/acp/VisualProofToolPreview.tsx:64 - Direct non-image visual-proof uploads without a session artifact resolve to link, but this returns null while AcpToolMessage suppresses details. The transcript therefore shows a blank, non-clickable tool row; retain a clickable fallback or preserve the tool details.

_{Reviewed 99a8dff}