Cartesia ink-2 STT; Respeecher TTS plugin added

What's Changed

• (openai realtime): add status_details to incomplete response logs by @tinalenguyen in https://github.com/livekit/agents/pull/5873
• feat(cartesia): add ink-2 stt by @charlotte-zhuang in https://github.com/livekit/agents/pull/5827
• fix(ipc): bound AgentSession.aclose() during job shutdown by @longcw in https://github.com/livekit/agents/pull/5875
• fix(amd): defer no-speech timer until SIP call is answered by @chenghao-mou in https://github.com/livekit/agents/pull/5848
• chore(tests): update tests to use Inference whenever possible AGT-2304 by @chenghao-mou in https://github.com/livekit/agents/pull/5632
• fix(llm): sort function tools to make order an invariant by @u9g in https://github.com/livekit/agents/pull/5884
• fix(deps): relax bithuman pin to <3 for SDK 2.x compatibility by @sgu-bithuman in https://github.com/livekit/agents/pull/5882
• fix(aws): flatten tool blocks when toolConfig is omitted by @u9g in https://github.com/livekit/agents/pull/5850
• fix(llm): serialize all provider tools for the Responses API + log server-side tool execution by @u9g in https://github.com/livekit/agents/pull/5865
• fix(llm): make to_responses_fnc_ctx.provider_tool_type optional by @toubatbrian in https://github.com/livekit/agents/pull/5892
• internal(voice): wire DebugMessage over remote-session wire by @toubatbrian in https://github.com/livekit/agents/pull/5855
• Add respeecher tts plugin by @mitrushchienkova in https://github.com/livekit/agents/pull/3233
• feat(plugins-google): add cached_content option for explicit context caching by @kamil-bidus in https://github.com/livekit/agents/pull/5675
• (google llm): ruff and add cache warnings by @tinalenguyen in https://github.com/livekit/agents/pull/5893
• feat(smallestai): update TTS plugin for Lightning v3.1 Pro and WebSocket streaming by @harshitajain165 in https://github.com/livekit/agents/pull/5799
• fix(openai realtime): honor OPENAI_BASE_URL env var fallback by @chenghao-mou in https://github.com/livekit/agents/pull/5895
• livekit-agents@1.5.15 by @github-actions[bot] in https://github.com/livekit/agents/pull/5896

New Contributors

• @sgu-bithuman made their first contribution in https://github.com/livekit/agents/pull/5882
• @mitrushchienkova made their first contribution in https://github.com/livekit/agents/pull/3233
• @kamil-bidus made their first contribution in https://github.com/livekit/agents/pull/5675

Full Changelog: https://github.com/livekit/agents/compare/livekit-agents@1.5.14...livekit-agents@1.5.15