Checks: Add MultipleCapitalCheck for issue #8753

[moonchoe]

Issue #8753
introduces a new quality check called MultipleCapitalCheck. It detects words that contain multiple consecutive or misplaced capital letters (like HEllo or CAmelCase), which are commonly typos.

Changes:

• Implemented MultipleCapitalCheck in weblate/checks/chars.py using the regex library to properly handle Unicode uppercase characters.
• Registered the new check in weblate/checks/models.py.
• Added regex to project dependencies in pyproject.toml.
• Added unit tests in weblate/checks/tests/test_chars_checks.py covering positive matches, negative matches (acronyms), and Unicode scenarios.

Verification:

• Passed all new unit tests via pytest.
• Passed code style and linting checks (ruff).

[nijel]

• For the check to be used it needs to be listed in the default set of checks in weblate/settings_docker.py and weblate/checks/models.py.
• Can you please add documentation and changelog entry?

[nijel]

The comment is useless.

[nijel]

Again, useless comment.