Fix and improve test: message_length_limit

[ttw225]

Description

This PR fixes how message_length_limit is resolved when the CLI flag is unset. Previously, the CLI argument could be present as None, causing arguments.get("message_length_limit", ...) to return None and skip the config fallback—so the configured limit (e.g. in pyproject.toml) was effectively ignored.

-        self.max_msg_length = arguments.get(
-            "message_length_limit", config.settings.get("message_length_limit", 0)
+
+        message_length_limit = arguments.get("message_length_limit")
+        self.message_length_limit: int = (
+            message_length_limit
+            if message_length_limit is not None
+            else config.settings["message_length_limit"]
         )

Now the precedence is correctly enforced as CLI > config > default (0 = no limit) for both cz commit and cz check, and additional unit + integration tests are added to prevent regressions.

• unit tests: test_commit_command.py, test_check_command.py
• integration tests: tests/test_cli_config_integration.py

Checklist

• I have read the contributing guidelines

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-with: [Cursor] following the guidelines

Code Changes

• Add test cases to all the changes you introduce
• Run uv run poe all locally to ensure this change passes linter check and tests
• Manually test the changes:
  • Verify the feature/bug fix works as expected in real-world scenarios
  • Test edge cases and error conditions
  • Ensure backward compatibility is maintained
  • Document any manual testing steps performed
• Update the documentation for the changes

Expected Behavior

When message_length_limit is configured, cz commit / cz check should enforce it unless explicitly overridden via -l/--message-length-limit (including -l 0 to disable the limit).

Steps to Test This Pull Request

Steps to reproduce the behavior:

1. Create a temp repo with a pyproject.toml containing:

[tool.commitizen]
name = "cz_conventional_commits"
message_length_limit = 10

2. Confirm config is enforced (should fail):
   cz check --message "feat: this is definitely too long"
3. Confirm CLI overrides config (should succeed):
   cz check -l 0 --message "feat: this is definitely too long"

Additional Context

#1899

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.99%. Comparing base (33223b4) to head (f5c4b48).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1900   +/-   ##
=======================================
  Coverage   97.99%   97.99%           
=======================================
  Files          60       60           
  Lines        2689     2691    +2     
=======================================
+ Hits         2635     2637    +2     
  Misses         54       54           

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