fix: windows case sensitivity in pkg cache variants uri

[maxnbk]

Closes #2101 .

Explanation:

get_package_from_uri in the filesystem package repository applied os.path.normcase to the entire URI before slicing out the package name and version. On Windows, normcase lowercases the whole string, silently corrupting mixed-case names (FooBar -> foobar) and versions (1.0B -> 1.0b) before they were used for lookup, causing both to return None.

Fix:

We scope the normcase usage to the is_subdirectory boundary check only. The subsequent name/version extraction slices from the original URI, preserving caller-supplied casing.

Disclosure:

This PR was AI-assisted with Claude Code, Sonnet 4.6, primarily for diagnostics, logic-tracing, documentation and edge-case verification.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.65%. Comparing base (d415b96) to head (f2dfcca).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2107   +/-   ##
=======================================
  Coverage   60.65%   60.65%           
=======================================
  Files         164      164           
  Lines       20584    20584           
  Branches     3579     3579           
=======================================
  Hits        12485    12485           
  Misses       7224     7224           
  Partials      875      875           

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