fix(a11y): resolve WCAG AA contrast failures in light theme and dashb…

[Antra1705]

Summary

Resolved WCAG AA color contrast failures in the modern-light-blue theme identified via Lighthouse accessibility audit. Three color token fixes across globals.css, StatsCard.tsx, and LandingPage.tsx.

Closes #1335

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Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• globals.css: Updated --accent from #5b8def (3.04:1) to #2563eb (4.85:1 — WCAG AA pass)
• globals.css: Updated --accent-secondary from #8eb7ff to #1d4ed8 (6.70:1 — WCAG AA pass)
• globals.css: Synced --focus-ring with updated primary accent
• StatsCard.tsx: Replaced hardcoded #6b7280 unit label color with #4b5563 (4.68:1 — WCAG AA pass)
• LandingPage.tsx: Replaced hardcoded #10b981 terminal comment color (2.46:1) with var(--success) token, resolving to #059669 in light mode (4.85:1)

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How to Test

1. Switch to modern-light-blue theme
2. Run Lighthouse accessibility audit — contrast failure should be resolved
3. Verify dashboard card unit labels and terminal mock comments are legible
4. Confirm no visual regressions in dark theme

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Screenshots (if UI change)

Before

After

Before

After

Before

After

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Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

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Accessibility Checklist

• Proper keyboard navigation tested
• Responsive UI verified
• Accessibility labels added where needed

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Additional Notes

• 20 pre-existing test failures exist on dev branch — confirmed identical before and after this PR (verified via git stash + npx vitest run). Zero new failures introduced.
• Contrast ratios verified using Chrome DevTools color picker and WebAIM contrast checker.
• Dark theme aesthetics preserved — fixes scoped to modern-light-blue theme tokens only.

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[github-actions]

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[github-actions]

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