Stabilize Meeting Lab pipeline for RC1 evaluation

This commit significantly improves the robustness and determinism of the Meeting Lab processing pipeline and establishes the first Release Candidate baseline for end-to-end evaluation.

Highlights

- BUG-009
  - Implement deterministic responsible-party validation
  - Normalize participant aliases using Meeting Context
  - Reject invalid responsible values (dates, locations, technical terms, projects, products, unknown entities)
  - Record structured responsibility validation metadata
  - Add focused regression tests

- BUG-010
  - Implement adaptive num_predict estimation for Semantic Consolidator
  - Eliminate JSON truncation caused by fixed output limits
  - Add deterministic source coverage repair
  - Preserve strict post-repair validation
  - Add regression tests

- BUG-011
  - Implement Working Protocol V2 renderer contract enforcement
  - Preserve raw renderer responses
  - Reject invalid protocol output instead of accepting malformed documents
  - Add deterministic cleanup for harmless formatting deviations
  - Add focused renderer regression tests

- Meeting Context
  - Validate Meeting Context V1
  - Integrate authoritative participant alias normalization

- Documentation
  - Update architecture documentation
  - Update output documentation
  - Update regression bug tracker

The pipeline now fails safely instead of silently accepting invalid intermediate or final artifacts.

Remaining work focuses primarily on extraction quality and semantic classification (decisions, action items, protocol faithfulness), rather than pipeline robustness.

docs/output-views.md

@@ -110,6 +110,21 @@ Characteristics:
 
 Completeness goal: optimize for recall and traceability.
 
+Current Working Protocol V2 renderer contract:
+
+- output must begin exactly with `# Working Protocol`
+- no explanatory preamble may appear before that heading
+- content is organized by topic with `##` topic headings
+- each topic may use only the supported `###` sections: `Background`,
+  `Decisions`, `Action Items`, `Open Questions`
+- category-level report framing such as a global `## Decisions` / `## Action
+  Items` summary is not a valid topic-oriented Working Protocol
+- raw model responses are preserved separately
+- deterministic cleanup may remove leading prose before an already valid
+  `# Working Protocol` heading and normalize harmless heading whitespace
+- `working_protocol.md` is written only after the cleaned candidate passes the
+  renderer contract validator
+
 ## Concise Distribution Protocol
 
 Suggested filename: `distribution_protocol.md`