feat: add native-style hotkey tooltips for quick nav linksDev

[ImXiangYu]

Summary

This PR improves quick-link keyboard shortcuts and tooltip UX in Better GitHub Navigation.

Changes

• Added shortcut mapping for preset links:
  • Dashboard: g d
  • Explore: g e
  • Trending: g t
  • Collections: g c
  • Stars: g s
• Added GitHub-style hotkey tooltips for quick nav links (hover/focus).
• Removed default browser title tooltip to avoid duplicate tooltip layers.
• Added runtime hotkey conflict detection and console warnings.
• Fixed tooltip binding issue so all quick-link buttons show tooltips (not only the first one).
• Refined tooltip visuals to better match native GitHub:
  • Tooltip background: #25292E
  • Keycap background: #59636E
  • Padding: 4px 8px
  • Regular font weight
  • No tooltip arrow
• Bumped patch version and regenerated userscript output (0.1.33).

Verification

• npm run build
• Manual check on GitHub pages:
  • all quick-link buttons show tooltips correctly
  • shortcut hints render correctly for each button
  • no duplicate tooltip behavior