fix(config_file): refuse breaklines in config dict

[mdevolde]

fix(config_file): refuse breaklines in config dict

Why the pull request was made

To avoid that, if a part of the config come from an untrusted source, a config value could break a line and insert other config params.

Summary of changes

• Check line breaks in config values and refuse them.

Screenshots (if appropriate):

Not applicable.

How has this been tested?

Applied local tests (inlcuding new ones about our issue).

Resources

Not applicable.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update (changes to documentation only)
• Refactor / code style update (non-breaking change that improves code structure or readability)
• Tests / CI improvement (adding or updating tests or CI configuration only)
• Other (please describe):

Checklist

• Followed the project's contributing guidelines.
• Updated any relevant tests.
• Updated any relevant documentation.
• Added comments to your code where necessary.
• Formatted your code, run the linters, checked types and tests.

[Copilot]

Pull request overview

This PR hardens LanguageTool local server config serialization by rejecting CR/LF characters that could escape the generated one-option-per-line config file format.

Changes:

• Adds a helper to reject \n and \r in config keys and encoded values.
• Applies the validation across language-specific options, path options, and schema-backed options.
• Adds parametrized tests for newline injection attempts in keys, scalar values, and list values.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
language_tool_python/config_file.py	Adds CR/LF validation during config encoding before temporary config file creation.
tests/test_config.py	Adds regression coverage for line-break injection in config serialization.

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