Fix 3hr and 6hr issue

[rbeucher]

This pull request introduces several improvements to the handling of time dimensions, sub-daily point-sampled data, and CMIP table support in the ACCESS-MOPPY codebase. The main focus is on ensuring WCRP TIME001 compliance for sub-daily outputs, improving flexibility for time axis handling, and adding support for additional CMIP tables. Below are the most important changes:

Time Dimension Handling and Compliance

• Enhanced the logic in load_dataset and _preprocess to canonicalize UM auxiliary time dimensions (time_0, time_1) to a single "time" axis, ensuring that only the relevant time axis is kept and others are dropped. This prevents issues with dimension inflation and improves dataset consistency.
• Improved detection of time-dependent variables by checking for any dimension starting with "time" rather than just "time", making the code more robust for datasets with multiple or nonstandard time axes. [1] [2]

Sub-daily Point-sampled Data Alignment

• Added the _align_subdaily_point_time_to_square_grid method to automatically shift sub-daily point-sampled time axes (e.g., those starting at 03:00 or 06:00) to align with canonical daily grid boundaries, as required by WCRP TIME001. This alignment is now invoked automatically before writing output. [1] [2]

CMIP Table and Frequency Support

• Added support for the "3hrPt" and "6hrPlevPt" CMIP tables throughout the codebase, including in the driver initialization, error messages, and frequency parsing. [1] [2] [3]

Example Configuration

• Updated the example batch configuration YAML to comment out an unmapped variable (seaIce.ts.tavg-u-hxy-si.mon.glb), clarifying expected mappings.

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.7%. Comparing base (f66a62d) to head (d592338).

Files with missing lines	Patch %	Lines
src/access_moppy/base.py	60.0%	5 Missing and 3 partials ⚠️

❌ Your patch check has failed because the patch coverage (60.0%) is below the target coverage (90.0%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #497     +/-   ##
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- Coverage   78.7%   78.7%   -0.0%     
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  Files         33      33             
  Lines       6558    6574     +16     
  Branches    1242    1245      +3     
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+ Hits        5163    5173     +10     
- Misses      1127    1131      +4     
- Partials     268     270      +2     

Flag	Coverage Δ
unit	78.7% <60.0%> (-<0.1%)	⬇️

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