Implement MonthlyCommitAndReviewActivityTrigger for collecting users with commit/review activity

[konard]

Summary

Implements a new GitHub bot trigger to solve issue #92: "Collect users who made commits and/or reviews in the specified month using GitHub Bot or GitHub API."

Key Features

• New Trigger: MonthlyCommitAndReviewActivityTrigger responds to issues with titles containing "monthly commit and review activity" or "collect users who made commits"
• Date Parsing: Extracts month and year from issue body in format month: X and year: Y
• Repository Filtering: Supports ignoring repositories via Lino-formatted links (ignore repo_name repository.)
• GitHub API Integration: Uses Octokit to fetch commits and pull request reviews within specified date range
• Comprehensive Results: Returns formatted list of users with their commit and review activities
• Error Handling: Provides helpful error messages and defaults to previous month if dates not specified

Usage Example

Issue Title: Monthly commit and review activity for November 2023

Issue Body:

month: 11
year: 2023

ignore test-repo repository.
ignore archived-repo repository.

Response Format:

# Users with commit and/or review activity in November 2023

**Total active users: 5**

## @alice
Activities (7):
- Commit in project-a: Add new authentication module
- Review in project-b: PR #123 - Update documentation
- ... and 5 more activities

Implementation Details

• GitHub API Usage: Leverages existing GitHubStorage class with Octokit
• Date Range Filtering: Searches commits and reviews within the entire specified month
• Activity Tracking: Records both commit messages and pull request review details
• Performance: Processes all organization repositories with proper filtering
• Integration: Seamlessly integrated with existing bot trigger system

Files Added/Modified

• csharp/Platform.Bot/Triggers/MonthlyCommitAndReviewActivityTrigger.cs - Main implementation
• csharp/Platform.Bot/Program.cs - Added trigger to IssueTracker
• examples/MonthlyActivityTrigger_Usage.md - Usage documentation
• examples/TestMonthlyActivityTrigger.cs - Test example

Test Plan

• Code compiles successfully with existing codebase
• Follows existing code patterns and conventions
• Integrates with existing trigger system
• Includes comprehensive error handling
• Provides clear usage documentation

🤖 Generated with Claude Code

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Resolves #92