detach losses when logging

[jveitchmichaelis]

Description

detach losses when logging. It's probable that lightning does this for us under the hood, but good to be clear.

@bw4sz want to try these fixes with your bird model branch?

I have also tried garbage collection, but I'm not sure it's necessary. Better to identify where we might be leaking.

Related Issue(s)

#1247

AI-Assisted Development

Some sanity checking with Claude Code, and an assisted review of where we might be missing resets etc.

• I used AI tools (e.g., GitHub Copilot, ChatGPT, etc.) in developing this PR
• I understand all the code I'm submitting

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.75%. Comparing base (0ab23a3) to head (04fb3d1).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1254      +/-   ##
==========================================
+ Coverage   87.73%   87.75%   +0.01%     
==========================================
  Files          20       20              
  Lines        2716     2720       +4     
==========================================
+ Hits         2383     2387       +4     
  Misses        333      333              

Flag	Coverage Δ
unittests	87.75% <100.00%> (+0.01%)	⬆️

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[bw4sz]

I agree that pytorch lightning should be doing this, but I don't see a downside for us to be sure.