Fix algorithm case preservation in DigestAuthMiddleware

[bdraco]

What do these changes do?

This PR fixes a case sensitivity issue in DigestAuthMiddleware where the algorithm name from the server's challenge was being converted to uppercase in the Authorization header response. Some servers (like Prusa printers) are case-sensitive and expect the exact algorithm case to be preserved.

The fix preserves the original algorithm case from the WWW-Authenticate challenge while still using uppercase internally for hash function lookups and algorithm type checking.

Are there changes in behavior for the user?

Yes, but only for users connecting to case-sensitive digest auth servers. The middleware will now preserve the exact algorithm case from the server's challenge instead of converting it to uppercase. This improves compatibility with servers that expect exact case matching (e.g., servers sending algorithm="MD5-sess" will now receive algorithm=MD5-sess instead of algorithm=MD5-SESS).

Is it a substantial burden for the maintainers to support this?

No. This is a minimal change that adds one variable to store the original algorithm case. The fix is backward compatible and doesn't change the API. The implementation is straightforward and includes comprehensive tests to prevent regression.

Related issue number

Fixes home-assistant/core#149196

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
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[bdraco]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.76%. Comparing base (eac0ef9) to head (d0bc3b1).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #11352   +/-   ##
=======================================
  Coverage   98.76%   98.76%           
=======================================
  Files         129      129           
  Lines       43375    43416   +41     
  Branches     2323     2324    +1     
=======================================
+ Hits        42838    42879   +41     
  Misses        383      383           
  Partials      154      154           

Flag	Coverage Δ
CI-GHA	98.64% <100.00%> (+<0.01%)	⬆️
OS-Linux	98.38% <100.00%> (+<0.01%)	⬆️
OS-Windows	96.80% <100.00%> (-0.01%)	⬇️
OS-macOS	97.68% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	97.32% <100.00%> (+<0.01%)	⬆️
Py-3.10.18	97.72% <100.00%> (-0.01%)	⬇️
Py-3.11.13	97.92% <100.00%> (+<0.01%)	⬆️
Py-3.11.9	97.52% <100.00%> (-0.02%)	⬇️
Py-3.12.10	97.62% <100.00%> (-0.01%)	⬇️
Py-3.12.11	98.02% <100.00%> (-0.01%)	⬇️
Py-3.13.5	98.28% <100.00%> (+<0.01%)	⬆️
Py-3.9.13	97.22% <100.00%> (-0.01%)	⬇️
Py-3.9.23	97.61% <100.00%> (-0.01%)	⬇️
Py-pypy7.3.16	89.70% <100.00%> (-2.52%)	⬇️
VM-macos	97.68% <100.00%> (+<0.01%)	⬆️
VM-ubuntu	98.38% <100.00%> (+<0.01%)	⬆️
VM-windows	96.80% <100.00%> (-0.01%)	⬇️

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[codspeed-hq]

CodSpeed Performance Report

Merging #11352 will not alter performance

_{Comparing digest_auth_preserve_case (d0bc3b1) with master (eac0ef9)}

Summary

✅ 59 untouched benchmarks

[patchback]

Backport to 3.12: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.12/6deeceafa55e17fbc9114c96188715fedbd46a7b/pr-11352

Backported as #11353

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.13: 💚 backport PR created

✅ Backport PR branch: patchback/backports/3.13/6deeceafa55e17fbc9114c96188715fedbd46a7b/pr-11352

Backported as #11354

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.