BOUNTY: AWS Comprehend PII redactor (issue #290)

[syutoutousai]

Summary

Implements a ComprehendRedactor class that integrates AWS Comprehend for PII detection and redaction, chainable with existing Endpoint classes via RxJS observables.

Changes

• New: ComprehendRedactor class in src/ai/src/lib/comprehend-redactor/
  • redact(text, piiTypes?) — async PII detection + masking
  • redact$(text) — Observable-based single-shot
  • mask$(source$) — chainable observable operator for piping with Endpoint classes
• Tests: 4 test cases covering redaction, type filtering, observable emit, and mask$ chaining
• Example: examples/pii-redaction/ demonstrating full pipeline (redact → LLM)
• Deps: @aws-sdk/client-comprehend, rxjs

Usage

const redactor = new ComprehendRedactor();
const { redacted } = await redactor.redact(userPrompt);
const response = await openai.chat({ prompt: redacted });

// Or chain with observables:
openai.chat$({ prompt }).pipe(redactor.mask$());

Closes #290

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