Summary

Added goodness-of-fit tests for the Student's t-distribution.

Solve the issue: #51

Quick changelog

• Implement several GoF statistics for Student's t-distribution:
  • Kolmogorov–Smirnov (KS)
  • Anderson–Darling (AD)
  • Cramér–von Mises (CVM)
  • Kuiper
  • Watson U²
  • Zhang Za / Zc
  • Lilliefors-type (parameters estimated)
  • Chi-square (binned)
• Add AbstractStudentGofStatistic base class and implementations in pysatl_criterion/statistics/student.py.
• Export new classes from init.py.
• Add unit tests: tests/statistics/test_student.py with:
  • Precomputed-value tests where appropriate (compared with scipy)
  • Basic property tests (positivity, finiteness, alternative handling)
  • Integration-style checks (location/scale, large df, edge cases)