v1.2.0

Release title: v1.2.0

Release body:

What's changed

• TypeScript public config contracts now use toolkit-owned structural interfaces: RTCEngine and RTMEngine
• AgoraVoiceAI.init() now accepts compatible RTC/RTM client objects without requiring as unknown as casts in strict package-manager layouts
• Public type surface no longer depends on agora-rtm event/class types (RTMClient, RTMEvents) for config and transcript event payload typing
• Tightened RTC structural typing with transcript-focused helper interfaces (RTCStreamMessageLike, RTCDataStreamParamsLike) and stricter RTCEngine.on/off overloads for 'stream-message' and 'audio-pts'
• Added development-time engine-shape validation in AgoraVoiceAI.init() with actionable error messages when required RTC/RTM methods are missing
• Improved public API discoverability with expanded JSDoc for AgoraVoiceAIConfig, renderMode, React hooks, and TranscriptHelperItem<T> generic typing

Added

• Interop type-check fixture: packages/conversational-ai/__typetests__/interop.ts with typecheck:interop script
• Coverage command surface (test:coverage) for root, core, and React packages
• CI coverage summary output in GitHub Actions step summary
• Additional lifecycle tests for invalid RTC/RTM engine inputs and React hook test coverage expansion

Upgrade notes

• Quick guide: see MIGRATION.md#11x---120 for 1.1.x -> 1.2.0.
• AgoraVoiceAIConfig.rtcEngine and RTMConfig.rtmEngine now use structural contracts (RTCEngine, RTMEngine) instead of peer SDK class/interface types.
• Existing real Agora RTC/RTM clients continue to work without code changes.
• If your app previously used casts (for example as unknown as), they are now redundant and can be removed.
• If you authored custom wrappers, ensure they implement the required methods:
  • RTC: on, off
  • RTM: publish, addEventListener, removeEventListener
• Runtime checks now fail fast in development when required engine methods are missing; align custom test doubles with the structural contracts.
• Coverage policy now explicitly aligns with the configured Vitest thresholds in CONTRIBUTING.md.

agora-agent-client-toolkit-react

Changed

• Removed internal rtcEngine cast workaround when passing useRTCClient() into AgoraVoiceAI.init()

Full Changelog: v1.1.0...v1.2.0