Migrate to WhisperX for speaker diarization

Implement a sliding window audio buffer and update the transcriber to
use WhisperX for transcription, alignment, and speaker identification.
Update the pipeline to handle and store speaker-attributed transcripts.

Additionally, update the LLM processor's reasoning parameter to
"enable_thinking".

pyproject.toml

@@ -0,0 +1,7 @@
+[project]
+name = "dnd-helpers"
+version = "0.1.0"
+description = "Add your description here"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = []