feat: support Podcast generation

src/podcast/graph/state.py

@@ -0,0 +1,19 @@
+from typing import Optional
+
+from langgraph.graph import MessagesState
+
+from ..types import Script
+
+
+class PodcastState(MessagesState):
+    """State for the podcast generation."""
+
+    # Input
+    input: str = ""
+
+    # Output
+    output: Optional[bytes] = None
+
+    # Assets
+    script: Optional[Script] = None
+    audio_chunks: list[bytes] = []