fix(ui): make the shared active toggle state clearly visible

[pascalandr]

Summary

The shared active state of toggle buttons (.icon-toggle with aria-pressed, aria-expanded or data-active) was nearly invisible on light palettes. On the default light palette the active fill was ΔE 0.4 from the header surface, so search, command palette, web preview, utility windows and panel toggles gave almost no feedback.

The single shared rule now fills active toggles with a uniform accent tint: 40%, and 50% for active + hover. The ink is accent leaning 20% toward the existing per-palette --text-on-accent.

• The icon keeps the text colour at ≥ 3:1 on every ready-made palette (lowest 3.34:1, Mist on hover).
• No per-palette values and no new tokens.
• Disabled toggles are excluded with zero-specificity :where().
• Corners stay square; the focus ring is unchanged.

Because the rule is shared, the tint also applies to every other active .icon-toggle: Files eye toggles, diff toggles, Missions toggles and the interruption dock's expand toggle.

Validation

• New icon-toggle-active.test.ts renders the real header on every ready-made palette and asserts:

  • ΔE ≥ 8 from the surface;
  • ΔE ≥ 6 from idle hover;
  • ΔE ≥ 2 between active and active + hover;
  • icon contrast ≥ 3:1.

  It fails on the previous rule.

• palette-quality.test.ts 40/40.

• UI typecheck clean.

• 11 browser suites: 124 pass, 1 Electron-only skip.

An independent gatekeeper review will be published before the admin merge.

[pascalandr]

Independent gatekeeper pass 1 on 7b91fc1: 2 P2 + 1 P3, merge held. Selectors and specificity are clean.

• P2-1 Mission past-run rows (mission-recurrence-list.tsx:248, mission-recurrence-reader.tsx:32) are full-width text list selections using .icon-toggle. Their text drops below 4.5:1 on the 40% tint over the canvas (Mist 4.19, Dawn 4.03, Linen 4.22, Sage-light 4.23; more palettes at 50%). Fix: use the shared --list-item-highlight-* selection tokens there, as AGENTS.md specifies for Mission selection.
• P2-2 SpeechActionButton (aria-pressed while playing) sits on message cards (surfaceMuted). Icon contrast while playing + hover is 2.94 on Mist and 2.99 on Dawn, so "≥ 3:1 on every palette" is false off the header surface. Fix: sample the message-card surface in the test and retune until both surfaces pass.
• P3 AGENTS.md wording: the tool-output rail override is a legitimate existing exception, and the contrast claim should name the surfaces actually covered.

Verified: specificity (.tool-call-output-rail override still wins), no double tint, --text-on-accent available for built-in and custom palettes, oklab color-mix support, forced-colors unchanged, disabled exclusion, deterministic test. Typecheck; palette-quality 40/40; icon-toggle-active 1/1; header-windows 41/41; git-history 18/18; interruption-dock 19/19; mission-panel-layout 6/6; view-menu 2/2. Fixes and another pass follow.

[pascalandr]

Independent gatekeeper pass 2 on bdfe1d1: ZERO FINDINGS.

All three pass-1 findings are fixed:

• Past-run rows: they now use list-highlight selection; selected text is ≥ 4.82:1.
• Icon contrast: independently measured ≥ 3.20:1 across 17 palettes × 7 real surfaces; the Mist assistant card went from 2.94 to 3.26.
• AGENTS.md: the wording is accurate.

The per-rule --icon-toggle-active-ink approach keeps specificity, transitions and the output-rail override intact; no text rows still use .icon-toggle; the fixture change is isolated to ?assistant.

Validation: typecheck clean; palette-quality 40/40; icon-toggle-active 1/1; header-windows 41/41; git-history 18/18; interruption-dock 19/19; mission-panel-layout 6/6; mission-recurrence 16/16; view-menu 2/2; mission-passage-history 6/6.

Proceeding with the requested admin merge.