feat: add PII and credential auto-redaction in smartRemember

[buer5]

PR 7: feat/pii-filtering

Summary

• Add sanitizePIIAndCredentials function in smart-remember.ts to redact API keys, Slack tokens, passwords, bearer tokens, and email addresses.
• Integrate the filter at the smartRemember entry point so all downstream writes operate on sanitized content.
• Add unit test covering PII redaction in smart-routing.test.mjs.

Why

The remember() interface has no content filtering — sensitive data like API keys (sk-proj-...), Slack tokens (xoxb-...), passwords, and emails can be persisted in plaintext to local Markdown/JSON files, creating a security risk if the memory directory is shared or leaked.

Tests

npm run build
npm test

Test output:

✔ Smart routing — smartRemember
  ✔ filters PII and credentials in smartRemember (445.9274ms)

Note

Non-sensitive content passes through unchanged. The filter runs only at the smartRemember entry point, so there is zero performance impact on read paths.