feat(web): add lightbox preview for chat images

[techotaku39]

Summary

• extract the zoomable image viewer from the file page into a reusable ImagePreview component
• use the same full-screen viewer for chat image attachments
• make generated-image chat cards click-to-preview with the same zoom/pan controls

Reason

Chat images were only visible as small inline previews. Unlike the file viewer, clicking a chat image did not open a larger preview, which made screenshots and generated images hard to inspect on mobile.

This keeps the existing thumbnail layout, but lets users tap the image to open the full-screen viewer with zoom, pan, double-click reset, Escape close, and the existing file-viewer controls.

Related

• Related to [Enhancement] Render images inline in tool results and attachments with lightbox preview #508, which also proposes lightbox previews for image attachments and broader inline image rendering in tool results.
• I also noticed feat(web): inline image rendering in tool results with lightbox preview #509 is an older open PR for the broader [Enhancement] Render images inline in tool results and attachments with lightbox preview #508 scope. This PR is intentionally narrower and reuses the image viewer that already exists in the file page.

Test

• npm exec -- bun run typecheck:web

[github-actions]

Findings

• No high-confidence findings.

Summary

• Review mode: initial
• Reviewed the full latest diff for image attachment lightbox reuse across chat attachments, generated-image cards, and the file viewer. No correctness, security, data-loss, performance, or maintainability issue above the reporting threshold found in the added/modified lines.
• Residual risk: web UI interaction coverage remains manual; no existing web tests cover the lightbox gestures or chat attachment preview flow.

Testing

• Not run (automation): bun run typecheck:web could not run because bun is not available on PATH in this runner.

HAPI Bot