Enable parallel runners for golangci-lint

[JAORMX]

Summary

• Add --allow-parallel-runners flag to all golangci-lint run invocations in the Taskfile
• This allows multiple golangci-lint instances to run simultaneously by preventing the default file lock acquisition at startup

Test plan

• Run task lint and verify it works as before
• Run task lint-fix and verify it works as before

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.89%. Comparing base (db08b51) to head (3b8c2ae).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3701      +/-   ##
==========================================
- Coverage   65.89%   65.89%   -0.01%     
==========================================
  Files         417      417              
  Lines       41213    41213              
==========================================
- Hits        27157    27156       -1     
  Misses      11959    11959              
- Partials     2097     2098       +1     

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