refactor: Remove observed total latency from metrics calculations

refactor: Remove LLM to TTS handoff latency from metrics and UI

feat: Enhance metrics collection and turn tracing for assistant responses

feat: Enhance metrics collection and tracing for assistant text

feat: Enhance metrics collection and assistant item correlation

feat: Enhance turn tracing and metrics collection

codex fixex

feat: Enhance voice activity detection and turn tracing features

feat: Add Langfuse tracing support and UI enhancements

feat: Enhance turn pipeline summary with partial updates and tool activity tracking

feat: Introduce turn pipeline summary and enhance tool execution metrics

feat: Enhance metrics collection with event timestamps for assistant interactions

feat: Enhance assistant behavior and tool feedback mechanisms

feat: Add post-tool response timeout and enhance error handling in channel metrics

feat: Enhance metrics collection and tracing with speech_id support

refactor: Restructure agent components and remove unused files