Add tests for enhanced error handling and additional coverage

[starichkov]

• Expand test cases for init, restore, moveToRecycleBin, and permanentDelete methods in CouchDB and MongoDB repositories.
• Introduce base NoteRepository tests for unimplemented methods.
• Ensure backward compatibility of API server exports.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.45%. Comparing base (d61a157) to head (4272fdb).

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
+ Coverage   97.65%   99.45%   +1.80%     
==========================================
  Files           7        7              
  Lines         554      554              
  Branches       82       82              
==========================================
+ Hits          541      551      +10     
+ Misses         13        3      -10     

Flag	Coverage Δ
unittests	99.45% <ø> (+1.80%)	⬆️

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