Accessibility audit and WCAG fixes for dapp auth and dashboard

[Cbiux]

Summary

Accessibility audit (WCAG 2.1 AA) for dapp auth and dashboard — keyboard nav, focus states, ARIA labels, color contrast.

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Scope

Area	Files
Auth	Front/components/wallet-auth-card.tsx, /login, /register
Dashboard	dashboard-nav.tsx, score cards, history table
Admin	Front/app/admin/page.tsx
Shell	Front/components/dapp-shell.tsx

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Checklist

• All interactive elements reachable via Tab
• Visible focus ring on buttons/links (not removed by outline-none without replacement)
• Form inputs have associated <label> or aria-label
• Error alerts use role="alert" / Alert components correctly
• Color contrast ≥ 4.5:1 for body text on dark background
• History/admin tables: scope on headers, caption or aria-label
• Wallet connect button describes action for screen readers

Tooling: axe DevTools, Lighthouse accessibility, optional @axe-core/playwright in #36 E2E.

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Acceptance criteria

• Lighthouse accessibility score ≥ 90 on /login and /dashboard
• Zero critical axe violations on scoped pages
• Document findings + fixes in PR description
• No visual regression to brand (dark theme preserved)

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Out of scope

• Full WCAG legal audit
• Landing site (separate repo)

[snkk2x-collab]

/attempt #67