fix: enable LaTeX rendering and update test reference data

[biofe]

Summary

• Enable text.usetex = True in _apply_style() and kinetic_network.py so that LaTeX renders Latin Modern Roman correctly (previously, latex=False calls silently fell back to DejaVu Sans)
• Remove all latex=False arguments from pplt.use_style() calls to ensure consistent LaTeX rendering across all plot functions
• Extend TestFontFamily tests to verify both text.usetex=True and correct font.family at save time
• Regenerate 10 doc plot PNGs with correct LMR font
• Update baseline Z/macrostate files to match current stable-sort algorithm
• Regenerate tests/data/HP35/expected_output/gpcca/Z.npy to match current GPCCA+lumping code

Test plan

• All TestFontFamily tests pass (verify LaTeX + LMR at savefig time)
• All regression baseline tests pass (test_generated_z_matches_baseline, test_generated_macrostate_assignment_matches_baseline)
• test_HP35_gpcca passes
• Full suite: 72 passed, 7 deselected (known missing-data tests)