fix(venv): escape glob characters in the venv lookup prefix

[MohammedAlkindi]

get_venv_prefix builds the prefix from the project directory name, and venv create writes that name to disk literally. iter_venvs then feeds the same string to Path.glob, where [ and ] are pattern metacharacters and are legal in Windows directory names. A project in my[project], or the common browser-download form downloads[1], produces a pattern that never matches its own venv, so venv list, venv remove, venv activate, pdm use --venv and interpreter discovery all silently see nothing. No error is raised.

On the unpatched source the added test reports:

assert {} == {'3.13': WindowsPath('.../venvs/downloads[1]-dS0SdxMQ-3.13')}

iter_venvs yields nothing while the venv it should find is on disk.

glob.escape rather than iterdir() and startswith, because glob returns empty for a missing venv parent directory while iterdir() raises FileNotFoundError, which is the normal state on a fresh machine. The ident slice keeps the unescaped length, since it indexes the real on-disk name rather than the pattern.

Scoped suite on Windows 11, CPython 3.13.5: 481 passed, 5 skipped.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.79%. Comparing base (bf6f64b) to head (3b5744c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3869   +/-   ##
=======================================
  Coverage   88.79%   88.79%           
=======================================
  Files         120      120           
  Lines       13321    13322    +1     
  Branches     2265     2265           
=======================================
+ Hits        11828    11829    +1     
  Misses        931      931           
  Partials      562      562           

Flag	Coverage Δ
unittests	88.68% <100.00%> (+<0.01%)	⬆️

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