fix(gui): dialog overlay frame and sticky Sub-agent focus ring

[Wibias]

Summary

• Request Logs detail uses a native <dialog class="modal-overlay">. Browser UA styles still draw a solid border plus a separate ::backdrop, which stacked on our full-screen tint and produced the white rectangular frame / double-dimmed background around the error modal.
• Closing Dashboard Sub-agent help restored focus to the circular info button with :focus-visible, so the focus ring stacked on the icon’s own circle (sticky double ring until you clicked elsewhere). Restore now uses focus({ focusVisible: false }) so keyboard a11y focus return stays, without the leftover mouse-close ring.

Screenshots

Test plan

• Open Request Logs → click a failed row → confirm full-screen dim with no white frame / double tint
• Close the log detail (X / Escape / backdrop) → overlay clears cleanly
• Dashboard → open Sub-agent info help → close it → info icon should not keep a double focus ring
• Tab to the Sub-agent info button → keyboard focus ring still appears

[lidge-jun]

Thanks — the white UA frame + double-dim diagnosis was exactly right, and it's landed on dev with your authorship preserved plus a maintainer repair:

• bfdaa3e9 — your PR fix(gui): dialog overlay frame and sticky Sub-agent focus ring #154 commit, absorbed as-is (author: @Wibias, source head 5e8f1aa).
• 30782a87 — maintainer repair (Co-authored-by: @Wibias) closing the review findings:
  1. focus({ focusVisible: false }) ran for keyboard closes too, so Escape users lost their focus indicator — input modality is now tracked window-wide and only pointer-originated closes suppress the ring;
  2. focusVisible support (Chrome 145+/FF 104+/Safari 18.4+) stays a progressive enhancement, with the origin tracking correct everywhere.

Render-verified in the browser: overlay clean, mouse close leaves no ring, Escape close paints the visible ring. Closing in favor of the dev-landed commits; ships with the next release.