feat(classification-spine): implement STATE-WP-0065 repo-anchored model

Replace the ad-hoc coordination-domain spine with the Repo Classification
Standard: 14 market domains, classification columns on managed_repos, and
workplans anchored by repo_id (topic_id optional).

- Add Alembic migration d8e9f0a1b2c3 with data backfill and workstream→workplan rename
- Add api/classification.py validation and register-from-classification tooling
- Expose workplan-first REST/MCP surface with legacy workstream aliases
- Add C-24 consistency rule and legacy domain frontmatter mapping
- Update dashboard repos page with category/capability/stake filters
- Update orientation docs; mark STATE-WP-0065 finished

api/routers/contributions.py

@@ -43,7 +43,7 @@ async def create_contribution(
         title=body.title,
         body_path=body.body_path,
         related_topic_id=body.related_topic_id,
-        related_workstream_id=body.related_workstream_id,
+        related_workplan_id=body.related_workplan_id,
         notes=body.notes,
         status=ContributionStatus.draft,
     )