feat: Add Weekly Performance Tracker with Corpus API integration

What does this MR do and why?

This MR adds a Weekly Performance Tracker feature that integrates with the Corpus API (standup audio recording system) alongside GitLab activity tracking.

Key Changes:

1. New Weekly Activity UI Page (ui/weekly_performance.py):

   • CSV upload for managing intern teams with columns: Team Name, Full Name, GitLab Username, Corpus UID
   • 7-day activity grid showing combined GitLab (commits, MRs, issues) and Corpus (standup audio) data
   • Audio player for standup recordings embedded in the daily activity cells
   • Week navigation to view historical data

2. Enhanced Corpus Client (infrastructure/corpus/client.py):

   • User resolution: Accepts both usernames and UUIDs, resolves usernames to UUIDs when needed
   • Optional date filtering: fetch_records() accepts optional start/end dates for client-side filtering
   • Updated default API endpoint to https://api.corpus.swecha.org
   • Added logging for debugging integration issues

3. CI/Config Updates:

   • Updated .gitlab-ci.yml and .pre-commit-config.yaml
   • Updated CHANGELOG.md with v1.0.0 release notes

4. Cleanup:

   • Removed deprecated test files (test_gitlab.py, test_users.py)

User Experience:

Users can now:

1. Upload a CSV with the team members (linking GitLab usernames and Corpus usernames)
2. View a weekly grid showing both code activity (commits, MRs, issues) and standup audio
3. Play standup recordings directly from the daily activity cells
4. Navigate between weeks to review historical performance

This enables team leads to track both code contributions and standup participation in a unified dashboard.

MR acceptance checklist

• Code follows project conventions (Ruff, MyPy)
• Tests added/updated for new functionality
• Documentation updated (CHANGELOG)
• No breaking changes to existing features