Add SmallestSTTService using the Pulse WebSocket API for real-time
transcription. Includes SmallestSTTSettings dataclass, 32-language
support with resolve_language fallback, VAD-driven finalize signal,
and SMALLEST_TTFS_P99 latency constant.
Also adds X-Source and X-Pipecat-Version headers to Smallest STT
and TTS WebSocket connections.
Example files like openai.py shadow installed packages when Python adds the
script directory to sys.path. Prepend the parent folder name to each example
file (e.g. openai.py -> function-calling-openai.py). Also split
thinking-and-mcp/ into separate mcp/ and thinking/ directories.
Replace the nested services/speech/ and services/function-calling/ with
top-level voice/ and function-calling/ directories. Update eval script
paths and README to match.
