add calc_ocean.py for ocean variables calculation and update calc_utils.py

[rhaegar325]

Add Generic Calculation Functions for Ocean Variable Processing

What

Added generic calculation helper functions to standardize variable transformations:

• power(var, exponent) - Generic exponentiation (e.g., var**2)
• multiply(var, factor) - Scalar multiplication (e.g., unit conversion)
• sum_vertical(var, dim) - Vertical dimension integration

Also organized existing ocean calculation functions:

• K_degC(ctx, var, inverse) - Temperature unit conversion

Files Modified

• src/access_mopper/calc_util.py - New generic functions
• src/access_mopper/calc_ocean.py - Organized ocean-specific functions

Notes

✅ No breaking changes - functions are additive
✅ Backward compatible with existing code
✅ Tested with sample ocean model data

[codecov]

Codecov Report

❌ Patch coverage is 0% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.34%. Comparing base (0eb8d0e) to head (234f15e).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/access_moppy/derivations/calc_ocean.py	0.00%	12 Missing ⚠️
src/access_moppy/derivations/calc_utils.py	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #167      +/-   ##
==========================================
+ Coverage   52.02%   60.34%   +8.32%     
==========================================
  Files          18       19       +1     
  Lines        2722     2749      +27     
==========================================
+ Hits         1416     1659     +243     
+ Misses       1306     1090     -216     

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[rbeucher]

I think we already have standard funtions for this

ACCESS-MOPPy/src/access_moppy/derivations/__init__.py

Line 12 in 136911d

custom_functions = {

[rhaegar325]

oops, I missed that one.