feat(tools): add Power BI integration for dataset refresh and report export

[hh3538962]

Summary

Adds Power BI integration to enable agents to refresh datasets and export reports programmatically.

Relates to #3973

Changes

• ✅ Created power_bi_tool/ integration module
• ✅ Implemented OAuth2 authentication via credential store
• ✅ Added power_bi_get_workspaces() function
• ✅ Added power_bi_refresh_dataset() function
• ✅ Error handling and timeout management
• ✅ Basic README documentation

TODO (before final review)

• Add power_bi_export_report() function
• Add power_bi_get_datasets() function
• Add power_bi_get_reports() function
• Add unit tests
• Complete documentation with usage examples

Testing

• Manual testing pending (requires Power BI credentials)
• Unit tests to be added

Timeline

• Day 1: ✅ Basic structure and 2 core functions
• Day 2: Add remaining functions and tests
• Day 3: Complete documentation and testing
• Day 4-5: Address review feedback