fix: Handle write failures when printing --help/--version

[Xylphy]

Fixes #622

Summary

Make print_help and print_version write via the Dependencies output and return Result; propagate errors from do_find so find_main exits with a non-zero code instead of panicking.

[codecov]

Codecov Report

❌ Patch coverage is 76.47059% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.83%. Comparing base (3fb0a98) to head (6c05ce0).

Files with missing lines	Patch %	Lines
src/find/mod.rs	76.47%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #656      +/-   ##
==========================================
+ Coverage   91.76%   91.83%   +0.06%     
==========================================
  Files          31       31              
  Lines        6203     6231      +28     
  Branches      328      328              
==========================================
+ Hits         5692     5722      +30     
  Misses        390      390              
+ Partials      121      119       -2     

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