fix: raise contrast of tertiary text to WCAG AA

[xsmyile]

Tertiary text moves up one zinc step (to zinc-600 on hover/focus surfaces), light-mode accent text to orange-700 / amber-700 / red-700, and icon-only controls to zinc-500 in light, so across all five palettes the weakest text is 4.56:1 (light) / 5.18:1 (dark) and the weakest icon control 4.20:1 / 3.26:1, with hover and focus states never weaker than rest.

[pullfrog]

Important

Contrast improves, but some updated text still misses the stated WCAG AA target on interactive backgrounds.

Reviewed changes across all nine frontend components, including the surrounding backgrounds and hover/focus states.

• Tertiary text and placeholders: Light text moves to zinc-500 and dark text to zinc-400 across message details, inbox metadata, settings, status indicators, and undo hints.
• Tinted controls: Inactive filter chips and segmented-switch labels gain stronger light-mode colors, with stronger filter-chip hover colors.

Verification used source inspection and WCAG contrast calculations from the palette OKLCH values; no build or browser tests were run.

  ^{｜ Fix all ➔ ｜ Fix 👍s ➔ ｜ View workflow run ｜ Using gpt-6.1-sol ｜ 𝕏}

[pullfrog]

ℹ️ No new issues found in this delta. Approval is still pending the existing, unresolved tertiary-text contrast thread; its affected hover/focus styles are unchanged.

Reviewed changes since 5a1fa26, with the full PR diff checked for context.

• Strengthened accent text: Raised light-mode accent labels and destructive-button text to darker orange, amber, and red shades, with separate dark-mode colors.
• Improved icon controls: Increased contrast for star, copy, dismiss, and settings-close controls and adjusted relevant hover colors.

Verification used source inspection and dependency-free WCAG contrast calculations. No build or browser tests were run.

  ^{｜ Fix it ➔ ｜ View workflow run ｜ Using gpt-6.1-sol ｜ 𝕏}

[pullfrog]

✅ No new issues found.

Reviewed changes since 901143b, with the full PR diff checked for context.

• Fixed hover contrast: Raised attachment sizes, link metadata, and inbox dates, previews, and overflow counts to light zinc-600 on hover, while preserving dark zinc-400.
• Fixed focused-placeholder contrast: Raised the tag-input placeholder to light zinc-600 on focus, while preserving its dark-mode color.

Source inspection and contrast calculations confirm the previously flagged combinations pass AA. No build or browser tests were run.

  ^{｜ View workflow run ｜ Using gpt-6.1-sol ｜ 𝕏}