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.

docs/pipeline.md

@@ -67,6 +67,12 @@ Output View Rendering
 
 Each stage receives a well-defined input and produces a well-defined output.
 
+Meeting Context V1 exists as a manually maintained YAML metadata scaffold. It
+is implemented for validation, optional `--meeting-context` use during chunk
+extraction, deterministic prompt injection and minimal extraction JSON
+provenance. Later Canonicalizer, Semantic Consolidator, Canonical Meeting
+Knowledge and renderer integration remains future work.
+
 ---
 
 # Stage 1 – Normalization
@@ -284,6 +290,22 @@ Each extractor has:
 - one responsibility
 - one output schema
 
+The current shared extraction prompt is assembled from:
+
+- `common.md`
+- `decisions.md`
+- `todos.md`
+
+The todo prompt requires explicit assignment, volunteering or acceptance before
+recording a named responsible person. Meeting Context may validate identity,
+role, department and attendance, but never establishes responsibility.
+
+The decision prompt treats a personal commitment to concrete future work as a
+todo unless the group separately establishes a binding outcome, rule, approval,
+rejection, deferral, selection, process state or responsibility policy. The
+same proposition should not be duplicated under decisions and todos; extract
+both only for semantically separate propositions.
+
 ## Processing Type
 
 LLM