Refactor bounds.yml to use multiple user messages

prompts/bounds.yml

@@ -1,6 +1,6 @@
 id: dnd.session_bounds
 version: "1.0.0"
-default_profile: local-gemma4
+default_profile: openrouter-gemini-flash
 description: Review D&D session transcript and identify starting and ending segments for actual gameplay.
 inputs:
   - name: transcript
@@ -12,6 +12,9 @@ messages:
     content_file: ./bounds.system.md
   - role: user
     content_file: ./bounds.user.md
+  - role: user
+    content: |
+      {{input "transcript"}}
 output:
   format: json
   validation_mode: json_schema