streaming(reader): cleanup chunk lock files by prefix during delete

[jwills]

Fixes #682

Centralizes chunk lock-file cleanup in Reader’s delete path and makes it compression-agnostic by removing any .lock files matching the chunk’s base filename prefix. Adds a test that simulates a non-local downloader which leaves lockfiles in place to ensure cleanup is effective.

Anyone in the community is free to review the PR once the tests have passed.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84%. Comparing base (a543725) to head (5f8ea89).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #683   +/-   ##
===================================
  Coverage    84%    84%           
===================================
  Files        52     52           
  Lines      7021   7023    +2     
===================================
+ Hits       5900   5904    +4     
+ Misses     1121   1119    -2     

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[deependujha]

great contribution @jwills and thanks GPT5. 🚀

[tchaton]

Thanks 😊