style: lint and format src/djehuty/web/validator.py with ruff, enforce

[641e16]

Note: Stacked on #173. only the last two commits are new here;
I'll rebase onto main once #173 merges.

Summary

Next slice of the incremental Ruff rollout (#66): lints and formats src/djehuty/web/validator.py and adds it to the enforced scope. Split into a mechanical commit (pure ruff check --fix + ruff format output, safe to skim) and a manual commit (the two violations ruff could not auto-fix, worth review).

Changes

• src/djehuty/web/validator.py (commit 1, mechanical): apply ruff check --fix (import sorting) and ruff format. No functional
  changes.
• src/djehuty/web/validator.py (commit 2, manual): iterate over value.values() where the loop key was unused (B007); keep the ValidationException name with a justified noqa: N818 comment (see Notes).
• justfile: add the file to lint_paths so just lint and CI enforce it.

Approval Checklist

• I agree to follow Djehuty's code of conduct.
• I have read and I have follow the code contribution workflow.
• Code style and conventions were respected.
• Documentation has been updated where needed (README, docs, or examples).
• Review approved by at least one maintainer.
• Merge readiness (PR is squashed into a single commit and follows the commit template).

Issue Reference

Closes #146 (part of #66)

Screenshots

Green CI run on my fork with the Lint job covering the extended scope:
https://github.com/641e16/djehuty/actions/runs/29641379402

Notes

• !!! First noqa, called out explicitly: ValidationException keeps its name despite N818 (exceptions should end in "Error"). It is the base class of nine validator exceptions and is caught ~60 in wsgi.py, which is not yet in lintscope - renaming it here would drag a 10k-line unlinted file into a formatting PR. The rule stays enabled; this is a single documented exemption, revisitable when wsgi.py gets checked (if it will).
• The B007 fix (for v in value.values() instead of an unused key) is behavior-identical: the loop returns the first value either way.
• Verified: just lint green on the full scope; module imports cleanly; unit tests pass.

[codecov]

Codecov Report

❌ Patch coverage is 34.92063% with 164 lines in your changes missing coverage. Please review.
✅ Project coverage is 17.49%. Comparing base (1a4ecd1) to head (2bcba3e).

Files with missing lines	Patch %	Lines
src/djehuty/web/validator.py	21.35%	81 Missing ⚠️
src/djehuty/utils/convenience.py	33.33%	56 Missing and 2 partials ⚠️
src/djehuty/utils/rdf.py	56.89%	23 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #184   +/-   ##
=======================================
  Coverage   17.49%   17.49%           
=======================================
  Files          21       21           
  Lines       10217    10217           
  Branches     1977     1977           
=======================================
  Hits         1787     1787           
  Misses       8241     8241           
  Partials      189      189           

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