feat(miners): add sorting support to Miner Repo Standings views

[milosde111]

Summary

Adds sorting support to Miner Repo Standings across both card and table views for PR and Issue modes, improving repository ranking visibility and overall usability.

Included improvements

• Added shared sorting state for standings data (field + order)

• Enabled sortable table columns with interactive header sorting

• Added compact card-view sorting controls with direction toggle

• Applied mode-aware default sorting:

  • PR mode → Repo score descending
  • Issue mode → Discovery score descending

• Automatically resets default sorting when switching between PR and Issue modes

• Refined sort control UI for consistency with surrounding controls:

  • improved open/closed visual states
  • compact responsive sizing
  • theme-token-based styling without hardcoded colors

Scope

• Frontend-only Miner Repo Standings UI enhancements
• No backend, API, or scoring logic changes

Related Issues

Closes #1285

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other (describe below)

Screenshots

Before

before-sort.webm

After

after-sort.webm

Checklist

• New components are modularized/separated where sensible
• Uses predefined theme (e.g. no hardcoded colors)
• Responsive/mobile checked
• Tested against the test API
• npm run format and npm run lint:fix have been run
• npm run build passes
• Screenshots included for any UI/visual changes