fix(cz_customize): set commit_parser default that captures change_type

[bearomorphism]

Description

Set a conventional-commits-style default for CustomizeCommitsCz.commit_parser so that cz_customize users who configure changelog_pattern (and optionally change_type_map / change_type_order) but do not set their own commit_parser still get a changelog grouped by change type.

CustomizeCommitsCz previously inherited commit_parser = r"(?P<message>.*)" from BaseCommitizen. That default had no change_type named group, so the changelog generator (in commitizen/changelog.py::_render_into_changelog_tree) couldn't extract a change_type to group by — every commit ended up under change_type = None and the changelog rendered as a single ungrouped bullet list. This was the exact failure mode in #466.

Checklist

• I have read the contributing guidelines

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

• Yes (please specify the tool below)

Generated-by: GitHub Copilot CLI (Claude Opus 4.7) following the guidelines

Code Changes

• Add test cases to all the changes you introduce
• Run uv run poe lint locally; CI matrix (3.10–3.14 × linux/macOS/windows) passes
• Manually test the changes:
  • Verify the bug fix works on the exact reproducer from changelog generation is not working as expected in case of cz_customize? #466
  • Test edge cases: with/without scope, with/without breaking marker, no commit_parser configured
  • Ensure backward compatibility — all 66 existing cz_customize tests still pass; users who provided their own commit_parser see no change
• Update the documentation for the changes (the customize.md docs already describe commit_parser; the new default is described in the code docstring)

Expected Behavior

End-to-end on the exact repro from the issue (cz_customize with changelog_pattern + change_type_order, no explicit commit_parser):

## Unreleased

### feat
- **DL-4567**: new feature test

### fix
- **DL-1234**: qweqwe

### chore
- update deps

(Previously: a single ungrouped bullet list, no ### feat / ### fix / ### chore headings.)

Steps to Test This Pull Request

1. mkdir test && cd test && git init -b main && git config user.{name,email} test
2. Create .cz.yaml:

   commitizen:
     name: cz_customize
     version: 0.1.0
     customize:
       schema_pattern: '(feat|fix|chore|refactor|perf)(\(\S+\))?!?:(\s.*)'
       changelog_pattern: '^(feat|fix|chore|refactor|perf)(\(.+\))?(!)?'
       change_type_order: ["BREAKING CHANGE", "feat", "fix", "refactor", "chore", "perf"]

3. Make a few commits using conventional-commit style (feat: ..., fix(scope): ...).
4. cz changelog --dry-run — output should be grouped by ### feat, ### fix, etc.

Additional Context

Closes #466.

Implementation:

class CustomizeCommitsCz(BaseCommitizen):
    commit_parser = (
        r"^(?P<change_type>\w+)"
        r"(?:\((?P<scope>[^()\r\n]*)\))?"
        r"(?P<breaking>!)?:\s*(?P<message>.*)$"
    )

Same shape as the cz_conventional_commits parser, but with \w+ instead of a fixed type alternation, so it works for any cz_customize schema that follows <type>(<scope>)?!?: <message>. Users with non-conventional commit formats can still override via customize.commit_parser.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.23%. Comparing base (4b93a50) to head (a0ef51d).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1970   +/-   ##
=======================================
  Coverage   98.23%   98.23%           
=======================================
  Files          61       61           
  Lines        2779     2780    +1     
=======================================
+ Hits         2730     2731    +1     
  Misses         49       49           

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