Add TRT-LLM nsys profiling support

[nv-roverman]

Summary

• Allow TRT-LLM worker launches to be wrapped with an nsys profile prefix.
• Add a setup helper for containers where Nsight Systems is installed outside the default PATH.

Testing

• Not run separately for this split branch.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (sa-submission-q2-2026@fdb1be7). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/srtctl/backends/trtllm.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                    @@
##             sa-submission-q2-2026     #141   +/-   ##
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  Coverage                         ?   61.04%           
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  Files                            ?       48           
  Lines                            ?     4143           
  Branches                         ?        0           
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  Hits                             ?     2529           
  Misses                           ?     1614           
  Partials                         ?        0           

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