Apply spec review polish to patterns

Pattern 1: clarify the router lambda's inline comment so a reader
who lands mid-snippet without the surrounding prose still sees
the intent.

Pattern 3: switch state messages to list[Message] for consistency
with pattern 2, add the Message import, and use attribute access
(.content) rather than dict subscript at the read site.

Per spec review on PR #67.

Author: chris-colinsky

docs/patterns/parameterized-entry-point.md

@@ -48,7 +48,7 @@ def report(s: MissionState) -> dict:
 
 builder = (
     GraphBuilder(MissionState)
-    .add_node("router", lambda s: {})  # passthrough; routes from state
+    .add_node("router", lambda s: {})  # no state change; conditional edge below routes
     .add_node("plan", plan)
     .add_node("execute", execute)
     .add_node("report", report)

docs/patterns/session-as-checkpoint-resume.md

@@ -28,10 +28,11 @@ across resume).
 from typing import Annotated
 from openarmature.checkpoint import SQLiteCheckpointer
 from openarmature.graph import END, GraphBuilder, State, append, merge
+from openarmature.llm import Message
 
 
 class SessionState(State):
-    messages: Annotated[list[dict], append] = []
+    messages: Annotated[list[Message], append] = []
     facts: Annotated[dict[str, str], merge] = {}
     last_user_input: str = ""
 
@@ -73,7 +74,7 @@ async def handle_turn(session_id: str, user_input: str) -> str:
     # correlation_id; exact lookup is application-side bookkeeping.
     sessions_db.set_invocation_id(session_id, latest_for(session_id))
 
-    return final.messages[-1]["content"]
+    return final.messages[-1].content
 ```
 
 `sessions_db` is your application's session-state store (Postgres,