feat!: prepare AIWrapper 4.0.0 with live and speech APIs

[mitkury]

This prepares AIWrapper 4.0.0 by merging the full refactor-july-2026 branch into main. Applications gain persistent live model sessions, streaming speech providers, realtime voice agents, and native AWS Bedrock support, alongside fixes to provider streaming, cancellation, tool results, and agent lifecycle handling.

The package now uses the published aimodels 0.7.0 catalog (^0.7.0). The browser playground adds chat, transcription, synthesis, and live voice flows with shared provider settings and server-owned sessions. Build and CI checks cover the ESM package and browser playground, with credential-backed integration tests separated from deterministic checks.

Breaking changes and migration

• Require Node.js 20+ and use the declared ESM entry points: aiwrapper, aiwrapper/bedrock, and aiwrapper/speech. Undeclared deep imports are no longer exposed.
• Remove the exported LangVecs API; callers must migrate embedding functionality before upgrading.
• Replace Speech2Text.openai(...).ask(file) with SpeechToText.openai(...) and its audio session API (createSession, appendAudio, and finish).
• Replace the old TextToSpeech.elevenlabs(...).ask(text) object-URL result with the streaming speak(...) API. Supply an explicit voiceId and use voiceSettings in place of voice_settings.
• Install the optional @aws-sdk/client-bedrock-runtime peer and pass a configured client when using Bedrock. Direct browser requests remain subject to provider CORS support; privileged credentials should stay on the server.

See speech and live providers, realtime agents, and Bedrock for usage details.

Validation

• npm run check: package build, 177 unit tests, and package dry run passed with version 4.0.0.
• npm run check:playground: type check (zero errors or warnings), 35 tests, and production build passed with published aimodels 0.7.0; the subsequent change only updates the root package version.
• git diff --check passed for the release preparation changes.
• Credential-backed integration tests were not run in this release preparation.

This PR updates the package version without creating a release tag. The npm publish workflow runs when a v* tag is pushed.