refactor(code): reorganize test structure to test/ directory

[amondnet]

Summary

Reorganized test structure for packages/code to follow better organization patterns with dedicated test directories.

• Moved all tests from src/__tests__/ to test/ directory
• Created new test structure: test/unit/ and test/integration/
• Extracted parseArgs to src/utils/args.ts with bug fix for flag value parsing
• Extracted platform detection to src/utils/platform.ts
• Fixed CLI -v/--version and -h/--help flag handling
• Updated package.json test script to bun test ./test
• All 87 tests passing with new structure

Test plan

• All 87 unit tests passing
• All integration tests passing
• CLI version command works with both version command and -v/--version flags
• CLI help command works with both help command and -h/--help flags
• Format command works in both direct and stdin hook modes
• LSP command works in both direct and stdin hook modes
• Argument parsing handles edge cases correctly
• Platform detection works across environments

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 34.68%. Comparing base (cb7f71a) to head (6ad3868).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/code/src/utils/platform.ts	76.47%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   29.72%   34.68%   +4.96%     
==========================================
  Files           4       13       +9     
  Lines        1904     2606     +702     
==========================================
+ Hits          566      904     +338     
- Misses       1338     1702     +364     

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