Add optional Hampel filter support to H12 functions

[Tanisha127]

Closes #351

Summary

Added optional Hampel filter support to h12_gwss() and related plotting
functions. H12 GWSS results commonly include isolated outliers with high H12
values but little support from neighbouring windows. These are unlikely to be
true selection signals. The Hampel filter smooths these isolated outliers,
helping direct attention towards real recent selection signals.

Changes

• Added hampel_filter() function using median absolute deviation (MAD)
• Added three optional parameters to h12_gwss() and all related plotting functions:
  • apply_hampel (bool, default False) — enable/disable the filter
  • hampel_window (int, default 5) — window size for the filter
  • hampel_t (float, default 3) — threshold multiplier for outlier detection
• Updated docstrings for all affected functions
• Added unit test test_hampel_filter_removes_isolated_outlier
• Added Hampel filter checks inside check_h12_gwss and check_h12_gwss_multi

Functions Updated

• h12_gwss()
• plot_h12_gwss_track()
• plot_h12_gwss()
• plot_h12_gwss_multi_overlay_track()
• plot_h12_gwss_multi_overlay()
• plot_h12_gwss_multi_panel()

Testing

All 14 h12 tests pass locally.

[Tanisha127]

Hi @alimanfoo and @jonbrenas

This PR adds optional Hampel filter support to the h12_gwss() function and related plotting functions to help smooth isolated outliers. All 14 H12 tests pass locally, and all CI checks are green.
Please take a look when convenient? Happy to address any feedback.

Thanks!

[Tanisha127]

Hi @jonbrenas ,
All checks are now passing for this PR. Could you please review it when convenient?
Happy to make any changes if needed.
Thank you!

[jonbrenas]

Thanks @Tanisha127. Can you move the new parameters to the correct location?

[Tanisha127]

Hi @jonbrenas, I've addressed your feedback — the hampel parameters have been moved to the correct location (before chunks and inline_array) in all affected functions. All 17 tests are passing and all 8 CI checks are green. Please take a look when convenient!