GTI region cut

[hiyoneda]

I added a new class method to build a GTI based on spacecraft z-pointing direction, complementing the existing from_pointing_cut (point source + off-axis angle).

This method is needed for the pointing-aware binned image deconvolution (see #401).

• Add GoodTimeInterval.from_region_cut(region, sc_history, earth_occ, earth_occ_mode). It accepts a boolean Histogram with a HealpixAxis defining the on-region
• earth_occ_mode='all'/'any' controls how Earth occultation is evaluated across on-region pixels.

[codecov]

Codecov Report

❌ Patch coverage is 96.15385% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 72.81%. Comparing base (ef2e3f2) to head (bda2988).
⚠️ Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
cosipy/spacecraftfile/spacecraft_file.py	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
cosipy/event_selection/good_time_interval.py	94.52% <100.00%> (+1.13%)	⬆️
cosipy/spacecraftfile/spacecraft_file.py	84.23% <0.00%> (ø)

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[israelmcmc]

Thanks @hiyoneda . @parshadkp if you are available, can you review this one please?