[Feature] add korean business registration number recognizer

[RektPunk]

Change Description

This PR adds a new recognizer, KrBrnRecognizer, to detect and validate South Korean Business Registration Numbers.

Issue reference

Fixes #XX

Checklist

• I have reviewed the contribution guidelines
• I have signed the CLA (if required)
• My code includes unit tests
• All unit tests and lint checks pass locally
• My PR contains documentation updates / additions if required

[Copilot]

Pull request overview

This PR adds a new recognizer KrBrnRecognizer to detect and validate South Korean Business Registration Numbers (BRN), a 10-digit identifier used for business taxation purposes in South Korea.

Key Changes:

• Implements pattern-based recognition with checksum validation using a magic key algorithm
• Adds comprehensive test coverage with valid and invalid BRN test cases
• Integrates the new recognizer into Presidio's configuration system with disabled-by-default setting

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
presidio-analyzer/presidio_analyzer/predefined_recognizers/country_specific/korea/kr_brn_recognizer.py	New recognizer implementation with regex patterns, context words, and checksum validation algorithm for Korean Business Registration Numbers
presidio-analyzer/tests/test_kr_brn_recognizer.py	Comprehensive unit tests covering valid BRNs (with and without dashes), invalid BRNs (checksum failures, format errors), and edge cases
presidio-analyzer/presidio_analyzer/predefined_recognizers/country_specific/korea/__init__.py	Adds KrBrnRecognizer import and export, maintaining alphabetical order in all list
presidio-analyzer/presidio_analyzer/predefined_recognizers/__init__.py	Adds KrBrnRecognizer import and export to main predefined_recognizers module
presidio-analyzer/presidio_analyzer/conf/default_recognizers.yaml	Configures KrBrnRecognizer with Korean language support (ko/kr) and disabled-by-default setting (following country-specific recognizer convention)
docs/supported_entities.md	Documents the new KR_BRN entity type with description and detection method in the Korea section