KR_RRN context enhancement never fires on Korean-language text

Is your feature request related to a problem? Please describe.

KrRrnRecognizer.CONTEXT only contains English terms ("Korean RRN", "RRN", ...), so context enhancement never triggers for Korean-language documents, which is where RRNs most commonly appear. All other Korean recognizers already include Korean-language context terms (KrDriverLicenseRecognizer has "운전면허", KrPassportRecognizer has "여권", KrFrnRecognizer has "외국인등록번호"). KR_RRN is the only one missing them.

Describe the solution you'd like

Add Korean-language context terms to KrRrnRecognizer.CONTEXT: 주민등록번호 (resident registration number), 주민번호 (common abbreviation), 신분증 (ID card), 본인인증 (identity verification). These terms come from a production Korean PII-masking deployment.

I'd like to submit a PR for this.