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/architecture.md

@@ -188,6 +188,24 @@ Each extractor has exactly one task and one prompt.
 
 ---
 
+## Meeting Context
+
+Meeting Context V1 is a manually maintained YAML scaffold for reliable meeting
+metadata such as title, language, participants, aliases, departments,
+abbreviations and known entities.
+
+It is documented in `docs/meeting-context.md` and templated at
+`samples/templates/meeting_context.template.yaml`. It is implemented for
+loading, validation and optional injection into chunk extraction prompts.
+Extraction results record only minimal context provenance. It is not yet
+connected to consolidation, Canonical Meeting Knowledge or output rendering.
+
+The context can help prevent non-participants from being interpreted as
+attendees and can normalize known aliases for extraction. It must not infer
+roles, departments, responsibilities or decisions.
+
+---
+
 ## consolidation/
 
 Planned area for canonicalization and consolidation.
@@ -283,6 +301,7 @@ Implemented:
 - Transcript normalization
 - Technical chunk generation
 - Experimental LLM-based information extraction
+- Meeting Context V1 loading, validation and extraction prompt integration
 - Canonicalizer V1 deterministic extraction canonicalization
 
 The current extraction step still performs multiple tasks simultaneously.