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/schemas/contribution.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from pydantic import BaseModel, ConfigDict
+from pydantic import AliasChoices, BaseModel, ConfigDict, Field, computed_field
 
 from api.models.contribution import ContributionStatus, ContributionType
 
@@ -14,7 +14,10 @@ class ContributionCreate(BaseModel):
     title: str
     body_path: str | None = None
     related_topic_id: uuid.UUID | None = None
-    related_workstream_id: uuid.UUID | None = None
+    related_workplan_id: uuid.UUID | None = Field(
+        default=None,
+        validation_alias=AliasChoices("related_workplan_id", "related_workstream_id"),
+    )
     repo_id: uuid.UUID | None = None
     notes: str | None = None
 
@@ -36,10 +39,15 @@ class ContributionRead(BaseModel):
     status: ContributionStatus
     body_path: str | None = None
     related_topic_id: uuid.UUID | None = None
-    related_workstream_id: uuid.UUID | None = None
+    related_workplan_id: uuid.UUID | None = None
     repo_id: uuid.UUID | None = None
     submitted_at: datetime | None = None
     resolved_at: datetime | None = None
     notes: str | None = None
     created_at: datetime
     updated_at: datetime
+
+    @computed_field  # type: ignore[prop-decorator]
+    @property
+    def related_workstream_id(self) -> uuid.UUID | None:
+        return self.related_workplan_id