fix(types): add RegExp to Mode.keywords to match LanguageDetail.keywords

[KJyang-0114]

Summary

Fixes #4365 — TypeScript errors when dynamically importing language modules due to $pattern: RegExp in keywords not matching the type definition.

Root Cause

Language = LanguageDetail & Partial<Mode>

• LanguageDetail.keywords: string | string[] | Record<string, string | string[] | RegExp> ✅
• Mode.keywords: string | string[] | Record<string, string | string[]> ❌ (missing RegExp)

Since Language is an intersection, TypeScript requires the narrower Mode type to be satisfied. When language modules include $pattern: RegExp in their keywords object, the type check fails.

Fix

Updated Mode.keywords in types/index.d.ts to include RegExp:

- keywords?: string | string[] | Record<string, string | string[]>
+ keywords?: string | string[] | Record<string, string | string[] | RegExp>

Validation

• Build: npm run build ✅
• Test: npm run test ✅
• Type change is purely additive (no breaking changes)

Risk & Rollback

• Risk: Minimal — purely additive type change
• Rollback: Revert single line in types/index.d.ts