tuner: v3 UI polish — remove redundant selectors, click-outside close, style updates

[mogul]

Restored from slopsmith/slopsmith#806 — original issue, opened by @OmikronApex on 2026-06-11.
[restored-from: slopsmith/slopsmith#806]

Summary

The instruments panel (v3 topbar) already holds instrument/tuning/reference-pitch settings that were synced to the tuner plugin in v0.3.0. The tuner panel still shows two redundant dropdown selectors and a manual Close button that no longer fit the v3 UX pattern.

Changes

• Remove instrument and tuning dropdowns from the tuner panel — these settings now live in the instruments panel and are pushed to the tuner plugin on change
• Remove Close button — panel should close via click-outside or badge re-click (consistent with instruments panel behavior)
• Add click-outside-to-close — same { once: true } document listener pattern as the instruments panel; panel stops propagation on internal clicks; badge toggle gets stopPropagation so the opening click doesn't immediately close
• v3 Tailwind class updates — panel and sub-elements updated to fb-* color tokens (bg-fb-card, border-fb-border/50, text-fb-textDim, etc.) to match the instruments panel card style

Acceptance criteria

• Tuner panel has no instrument or tuning dropdowns
• Tuner panel has no Close button
• Clicking outside the open tuner panel closes it
• Clicking the tuner badge again closes the panel (toggle already worked; badge click should not re-open immediately after outside-click registration)
• Panel style matches instruments-panel card look in v3
• Plugin works correctly in both / (v2) and /v3