Implement Meeting Context V1 and extraction improvements

Introduce Meeting Context V1 with YAML schema, validation and template.
Support optional --meeting-context during chunk extraction.
Inject authoritative Meeting Context into extraction prompts.
Record Meeting Context provenance in extraction output.
Activate todos.md in shared prompt assembly.
Strengthen responsibility attribution and decision/todo boundaries.
Add focused Gold scenarios and validation tests.
Update architecture and pipeline documentation.

tests/gold/position_explicit_objection/README.md

@@ -0,0 +1,18 @@
+# position_explicit_objection
+
+Tests extraction of one explicit objection as a position.
+
+Scope:
+
+- Extract Tom's stated objection as exactly one position.
+- Do not create a todo for Tom.
+- Do not derive a decision from the objection.
+
+Exclusions:
+
+- This scenario does not test responsibility attribution for an open owner.
+- Responsibility attribution is covered by `responsibility_attribution_negative`.
+
+The transcript gives unique ground truth because Tom explicitly says "I object"
+and "My position is", then explicitly refuses responsibility. The group also
+states that no decision and no task for Tom were created.

tests/gold/position_explicit_objection/expected.json

@@ -0,0 +1,14 @@
+{
+  "facts": [],
+  "decisions": [],
+  "todos": [],
+  "questions": [],
+  "positions": [
+    {
+      "speaker": "Tom",
+      "position": "Tom objects to using one generic intake checklist because generic criteria will not work for analytics pilots and hardware trials.",
+      "evidence": "Tom: I object to that. My position is that generic criteria will not work for these two types of work."
+    }
+  ],
+  "technical": []
+}

tests/gold/position_explicit_objection/transcript.txt

@@ -0,0 +1,11 @@
+Iris: We could use one generic intake checklist for analytics pilots and hardware trials.
+
+Tom: I object to that. My position is that generic criteria will not work for these two types of work.
+
+Iris: Understood. Are you taking responsibility for rewriting the checklist?
+
+Tom: No. I am not taking that on, and I am not proposing an owner. I am only stating my position.
+
+Uma: Then we are not deciding the checklist today.
+
+Iris: Correct. No decision and no task for Tom.

tests/gold/responsibility_attribution_negative/README.md

@@ -7,9 +7,14 @@ The scenario includes a Marketing participant who comments critically on
 Business Development criteria. No one assigns that participant responsibility
 for defining the criteria, and the participant does not accept such a task.
 
-Expected behavior:
+Scope:
 
 - Do not assign Business Development criteria to the Marketing participant.
 - Do not reclassify the Marketing participant as Business Development.
-- Preserve the objection as a position.
 - Keep responsibility open unless explicitly assigned.
+- Preserve the agreed next step to ask Business Development for an owner.
+
+Exclusions:
+
+- This scenario does not test whether the objection is extracted as a position.
+- Position extraction is covered by `position_explicit_objection`.

tests/gold/responsibility_attribution_negative/expected.json

@@ -28,12 +28,6 @@
     }
   ],
   "questions": [],
-  "positions": [
-    {
-      "speaker": "Noah",
-      "position": "Noah says generic criteria will not work for different Marketing and product contexts.",
-      "evidence": "Noah: From Marketing, I can tell you that generic criteria will not work. A digital campaign and a physical product launch need different checks."
-    }
-  ],
+  "positions": [],
   "technical": []
 }