Fix phase-wrapped binning and add negative phase support

[jackieblaum]

Summary

• Fix IndexError when bins are empty: Added minlength parameter to np.bincount() to ensure array is long enough even when last bins have no data points
• Add support for negative phase ranges: Phases outside [0,1] (e.g., PHOEBE-style [-0.5, 0.5]) are now automatically normalized internally
• Fix phase-wrapped eclipses: Eclipses that cross the 0/1 boundary are now detected and unwrapped before binning
• Automatic rewrapping: Results are returned in the original phase space by default
• Version bump to 0.4.0 for PyPI release

Test plan

• All existing tests pass
• Added comprehensive tests for negative phase edge cases
• Added tests for phase-wrapped eclipse detection
• Verified binning works correctly with PHOEBE-style phase ranges