/claim #290

Summary

This PR implements the AWS Comprehend PII redaction utility for the JavaScript SDK as requested in #290.

Changes

• Add comprehendRedactor.ts in src/ai/src/lib/comprehend/

edactPII() - Detect and redact PII entities (SSN, email, phone, etc.)

• wrapChat() - Wrap any LLM endpoint to redact PII before/after
• subscribe() / pipe() - Observable-style chaining for redaction flows
• Add comprehendRedactor.test.ts with 7 Vitest test cases
• Add ws-comprehend-redaction example project
• Export types and helpers from src/ai/src/index.ts

Verification

• 7 Vitest tests all passing
• TypeScript compilation: no errors in changed files
• Prettier formatting: compliant