feat: Enhance miner repositories table with token score, filters, and pagination

[bittoby]

Changes

1. Token Score column and qualification filters

Added sortable "Token Score" column showing total token score per repository (merged PRs only). Added qualification filter buttons (All / Qualified / Unqualified) based on tier-specific requiredMinTokenScorePerRepo thresholds (Bronze: 5, Silver: 89, Gold: 144). Qualification counts are independent of tier filter, matching PR page behavior.

Before

After

2. Table UX improvements

• Added pagination (20 per page) with prev/next navigation
• Styled scrollbar matching PR page
• Header and filter bar always visible regardless of data/filter state
• Distinct empty messages: "No repository contributions found" vs "No repositories found for the selected filters"
• Responsive layout matching PR page

Before

After

Before

After

Test plan

• Verify Token Score column displays correct totals (merged PRs only)
• Verify qualification filters use correct tier thresholds
• Verify pagination works with filters and search
• Verify empty states show correct messages with filters visible
• Confirm all 46 existing tests pass