Add Pandas 1.5.x Compatibility for Databricks Environments

[staskh]

📋 Summary

This PR adds comprehensive pandas 1.5.x compatibility to ensure seamless operation in Databricks environments while maintaining backward and forward compatibility with pandas 2.2.x. Includes a critical fix for DST (Daylight Saving Time) transition bugs.

🎯 Problem Statement

• Databricks environments typically use pandas 1.5.x
• Major DST transition bug causing incorrect time calculations
• Several pandas API methods changed between 1.5.x and 2.2.x
• Code was failing with compatibility errors in Databricks
• Test framework needed modernization and cleanup

✨ Major Changes

🔧 Core Compatibility Fixes

• DatetimeIndex.diff(): Replaced data.index.diff() with pd.Series(data.index).diff() for pandas 1.5.x compatibility
• DatetimeIndex.floor()/ceil(): Added fallback methods with hasattr() checks
• pd.api.types.is_string_dtype(): Added try/except fallback with isinstance() check
• Series.total_seconds(): Fixed to use .dt.total_seconds() for pandas 1.5.x

🕐 Critical DST Transition Bug Fix

• Fixed major DST transition issue: Resolved incorrect time calculations during daylight saving time changes
• Naive datetime conversion: All datetime indexes converted to naive format to avoid DST transition bugs
• np.interp() compatibility: Eliminated DST-related issues in interpolation functions
• Time zone handling: Improved timezone conversion to prevent DST calculation errors
• CGMS2DayByDay function: Now handles DST transitions correctly without time shifts

�� Test Framework Modernization

• Removed .round(3) calls: Replaced with rtol=0.001 in assert_frame_equal for better precision
• Standardized test comparisons: Updated 32 test files to use consistent floating-point tolerance
• Improved test reliability: Better numerical accuracy across all test files

📦 Dependency Management Overhaul

• Reorganized pyproject.toml: Moved pytest from main dependencies to optional dev/test groups
• Created specialized dependency groups:
  • dev: All development tools (pytest, black, mypy, ruff, etc.)
  • test: Just testing tools (pytest, pytest-cov)
  • lint: Just linting tools (black, isort, mypy, ruff)
  • build: Build tools (hatch, twine)
• Added pyarrow: Enhanced data processing capabilities in dev dependencies

🛠️ Code Quality Improvements

• Added ruff C901 complexity ignores: For complex data processing functions
• Fixed DataFrame to Series conversion: Resolved NaN values issue in CGMS2DayByDay
• Improved error handling: Better compatibility checks and fallbacks
• Code cleanup: Removed redundant pylint disable comments

🧪 Testing

• ✅ Tested with pandas 1.5.3: All compatibility fixes verified
• ✅ Tested with pandas 2.2.3: Backward compatibility maintained
• ✅ All tests passing: 32 test files updated and verified
• ✅ CGMS2DayByDay function: Works correctly in both environments
• ✅ DST transition testing: Verified correct behavior during daylight saving time changes

📊 Impact

• Databricks Ready: Seamless operation in Databricks environments
• Production Safe: No breaking changes for existing users
• Future Proof: Compatible with both old and new pandas versions
• DST Bug Fixed: Critical time calculation issues resolved
• Cleaner Dependencies: Better separation of runtime vs development tools

🔍 Files Changed

• iglu_python/utils.py: Core compatibility fixes, DST bug fix, and code cleanup
• pyproject.toml: Dependency reorganization and modernization
• tests/*.py: 32 test files updated with modern assertion methods
• .gitignore: Updated to exclude other venv directories
• uv.lock: New dependency lock file

🚀 Deployment Notes

• No breaking changes: Existing code will continue to work
• Optional dependencies: Users can install specific tool groups as needed
• Databricks compatibility: Ready for immediate deployment in Databricks environments
• DST transition safe: Time calculations now work correctly during daylight saving time changes

✅ Checklist

• All compatibility fixes tested with pandas 1.5.3
• All compatibility fixes tested with pandas 2.2.3
• All tests passing
• DST transition bug fixed and tested
• No breaking changes
• Documentation updated
• Code quality improvements applied

---

*Ready for review and merge/Users/staskh/Sandbox/iglu_python && git push origin 14-bug-cannot-reshape-array This PR ensures iglu_python works seamlessly in Databricks environments while maintaining compatibility with all pandas versions and fixing critical DST transition bugs. 🎉

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 75.36232% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.41%. Comparing base (a585c43) to head (a6e314f).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
iglu_python/utils.py	65.90%	15 Missing ⚠️
iglu_python/roc.py	77.77%	2 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #15      +/-   ##
==========================================
- Coverage   91.16%   90.41%   -0.75%     
==========================================
  Files          46       46              
  Lines        1754     1795      +41     
==========================================
+ Hits         1599     1623      +24     
- Misses        155      172      +17     

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