MNT: Remove redundant wind_heading/wind_direction functions from EnvironmentAnalysis

[Gui-FernandesBR]

Summary

Removes the per-date/hour wind_heading and wind_direction Function objects that EnvironmentAnalysis stored inside original_pressure_level_data (and converted into converted_pressure_level_data). They were dead and redundant, and they carried a latent bug.

Motivation

While reviewing #974 (wind wraparound fix for the Environment class), we checked whether EnvironmentAnalysis needed the same fix. It does not — every consumer derives heading/direction from the wind velocity components (u/v) via arctan2, which is the correct circular method and immune to the 360°/0° seam:

• surface_wind_direction_by_hour → arctan2(vy, vx)
• average_wind_heading_profile / average_wind_heading_profile_by_hour → arctan2(mean_u, mean_v)
• wind_heading_profiles_list → arctan2(u(alt), v(alt))

The only code that interpolated raw degrees were these two stored Functions — and a usage audit shows they were never read anywhere (0 consumers), unlike their siblings wind_velocity_x/y, wind_speed, pressure, temperature. Because they linearly interpolated degrees, they reproduced the exact wraparound artifact that #974 fixes for Environment.

Changes

• Drop the wind_heading_function / wind_direction_function constructions and their dict assignments in the pressure-level data builder.
• Remove their now-unused entries from current_units and the converted_pressure_level_data conversion_dict.
• Update the builder docstring accordingly.

Heading/direction remain fully derivable from the retained wind_velocity_x / wind_velocity_y functions.

Verification

• ruff check / ruff format clean; pylint 10.00/10.
• tests/unit/environment/test_environment_analysis.py --runslow → 5 passed (exercises converted_pressure_level_data, wind_heading_profile_grid, average_wind_heading_profile, animate_wind_heading_profile).

Note for reviewers — API surface

These functions were technically reachable via the public original_pressure_level_data / converted_pressure_level_data properties, so strictly this is a public-API removal. They appear unused and undocumented as an access pattern, so I went with outright removal per the cleanup intent — but if you'd prefer a deprecation cycle instead, say so and I'll switch to that.

Split out of the #974 review; #974 stays scoped to the Environment class.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.22%. Comparing base (9cf3dd4) to head (4548e51).
⚠️ Report is 84 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1041      +/-   ##
===========================================
+ Coverage    80.27%   81.22%   +0.94%     
===========================================
  Files          104      113       +9     
  Lines        12769    14681    +1912     
===========================================
+ Hits         10250    11924    +1674     
- Misses        2519     2757     +238     

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