feat(analyzer): Add CaBnRecognizer for Canadian Business Numbers (CA_BN)

[Joey239716]

Change Description

Adds CaBnRecognizer for the Canadian Business Number (entity type CA_BN), a 9-digit business identifier issued by the Canada Revenue Agency.

• Detects the bare 9-digit form (weak pattern, 0.05, relies on context words) and the 15-character program account form such as 123456782 RT 0001 (medium pattern, 0.5), covering the common CRA program identifiers RT, RP, RC, RM, RR, RZ
• Validates every match with the Luhn checksum over the 9-digit base via invalidate_result (same scheme as CA_SIN), plus an all-same-digit guard since 000000000 passes Luhn
• Bilingual English/French context words (business number / numéro d'entreprise, CRA / ARC, GST / TPS, etc.)
• Registered in default_recognizers.yaml with enabled: false and en/fr support, following the CA_SIN and CA_POSTAL_CODE (feat: Add CaPostalCodeRecognizer for Canadian postal codes (CA_POSTAL… #2204) precedents
• Parametrized unit tests covering valid weak/medium forms, bilingual context, checksum failures, all-same-digit inputs, unknown program identifiers, and wrong lengths
• Documentation added to docs/supported_entities.md

Issue reference

Fixes #2206

Checklist

• I have reviewed the contribution guidelines
• I agree to follow this project's Code of Conduct
• I confirm that I have the right to submit this contribution and that it does not knowingly contain proprietary or confidential code.
• My code includes unit tests
• All unit tests and lint checks pass locally
• My PR contains documentation updates / additions if required

[Joey239716]

Hi @SharonHart, gentle nudge on this PR when you get a chance, Thanks!