feat: Add MCP server for Monarch Money integration

[eshaffer321]

Implements a Model Context Protocol (MCP) server that exposes Monarch Money data to AI assistants like Claude Desktop and Claude Code.

Features:

• 5 MCP tools: get_budget, get_transactions, get_accounts, get_categories, get_tags
• Unique rollover budget data (rolloverAmount, rolloverType) not in competitors
• Month selection for budgets (not just current month)
• Stdio transport for Claude Desktop/Code integration
• Built with official MCP Go SDK v1.0.0

Technical:

• Proper jsonschema validation for all tool inputs/outputs
• Comprehensive test suite (unit + integration tests)
• Server initialization validation test to catch startup issues
• Clean separation: main.go (setup), tools.go (implementations)

🤖 Generated with Claude Code

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Testing

• Unit tests pass
• Integration tests pass
• Manual testing completed

Screenshots (if applicable)

Additional Notes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 40.67%. Comparing base (3b17976) to head (b02b176).
⚠️ Report is 3 commits behind head on main.

❌ Your project status has failed because the head coverage (40.67%) is below the target coverage (70.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #11      +/-   ##
==========================================
+ Coverage   40.62%   40.67%   +0.05%     
==========================================
  Files          15       15              
  Lines        2186     2188       +2     
==========================================
+ Hits          888      890       +2     
  Misses       1233     1233              
  Partials       65       65              

Flag	Coverage Δ
unittests	40.67% <ø> (+0.05%)	⬆️

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