Fix keyboard navigation and ARIA labels in dashboard sidebar/nav

[bridgetthnkechi87-cloud]

Closes #294

Summary

• Added active-route accessibility support with aria-current="page"
• Added accessible labels and expanded/controls states for icon-only nav buttons
• Improved visible focus-visible styles for dashboard navigation controls
• Wired the mobile navigation menu so it can be opened, closed, and dismissed with Escape
• Extracted nav item matching into a shared helper and added tests

Testing

• pnpm --filter @guildpass/dashboard test apps/dashboard/test/nav-items.test.ts
• Result: 64 passed, 0 failed