test(client/config): add unit tests for ReadFromClientConfig and ReadDefaultValuesFromDefaultClientConfig

[Lil-Duckling-22]

Description

Adds comprehensive unit tests for ReadFromClientConfig and ReadDefaultValuesFromDefaultClientConfig functions to improve test coverage.

Tests cover:

• Config file creation when missing
• Reading existing config files
• Invalid TOML handling
• ChainID preservation
• HomeDir restoration

This addresses the gap in test coverage identified for these critical configuration functions.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.31%. Comparing base (ebdaf82) to head (3efdf4b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25734      +/-   ##
==========================================
- Coverage   70.32%   70.31%   -0.01%     
==========================================
  Files         839      835       -4     
  Lines       54441    54359      -82     
==========================================
- Hits        38285    38223      -62     
+ Misses      16156    16136      -20     

see 9 files with indirect coverage changes

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