Fix Sphinx docstring RST formatting warnings

Replace Markdown code blocks with RST syntax in genesys.py, fix
deprecated directive transitions in nvidia and summarization modules,
remove stray bullet prefix in whisper arg docs, restructure code block
in turn completion mixin, and add deepgram mock to Sphinx conf.

docs/api/conf.py

@@ -97,6 +97,8 @@ autodoc_mock_imports = [
     "fastapi.middleware",
     "fastapi.responses",
     "uvicorn",
+    # Deepgram dependencies
+    "deepgram",
 ]
 
 # HTML output settings