feat: implement variable team matchups with partner rotation

- Add manual team entry for permanent teams in Matchups tab
- Rename 'Teams' tab to 'Matchups' for clarity
- Implement partner rotation strategies (minimize_repeat, maximize_even, elo_based)
- Track partnerships across rounds to minimize repeat pairings
- Fix unit tests for team configuration and ELO calculations
- Add E2E test for 9+ participant tournaments with variable matchups

Key changes:
- TeamsSection.tsx: Added router.refresh(), manual team entry, and matchup display
- schedule-generator.ts: Enhanced generateVariableRoundRobin to track partnerships
- team-generator.ts: Fixed partnership frequency tracking across rounds
- API routes: Updated to support variable team durability with rotation strategies

FUTURE_WORK.md

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+# Future Work
+
+## Navigation Header Enhancement
+
+### Current Behavior
+- Admin users see an "Admin" link in the navigation header
+- Clicking "EuchreCamp" brand link goes to the home page
+
+### Proposed Change
+- Remove the "Admin" link from the navigation header
+- For **admin users**: clicking "EuchreCamp" brand link should take them to `/admin`
+- For **non-admin authenticated users**: clicking "EuchreCamp" brand link should take them to their player homepage (`/players/[id]/profile`)
+
+### Implementation Notes
+- This requires updating the Navigation component
+- Need to check user role/permissions in the Navigation component
+- May need to pass user info from server components to client Navigation
+
+### Related Files
+- `src/components/Navigation.tsx` - Main navigation component
+- `src/lib/auth-simple.ts` - Authentication utilities
+- `src/lib/permissions.ts` - Role checking utilities