feat(tts): add Edge-quality audio path

[jb-thery]

Summary

• add Edge/MP3 rendering to Mimir TTS with the same default voice and rate as the global Voice Forge skill
• keep Transformers.js WAV as the explicit offline/confidential path
• remove duplicated governance docs from package directories and point package READMEs to root project docs
• bump packages and CLI version to 0.4.1

Validation

• pnpm validate
• node packages/mimir/dist/cli.js --version
• node packages/mimir/dist/cli.js audio --engine edge --out /tmp/mimir-edge-test.mp3 --json
• release artifact tarball check for duplicated governance docs