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/decision.py

@@ -4,11 +4,16 @@ from datetime import datetime
 from pydantic import BaseModel, ConfigDict, model_validator
 
 from api.models.decision import DecisionStatus, DecisionType
+from api.schemas.compat import OptionalWorkplanIdCompatMixin
+from pydantic import AliasChoices, Field
 
 
 class DecisionCreate(BaseModel):
     topic_id: uuid.UUID | None = None
-    workstream_id: uuid.UUID | None = None
+    workplan_id: uuid.UUID | None = Field(
+        default=None,
+        validation_alias=AliasChoices("workplan_id", "workstream_id"),
+    )
     title: str
     description: str | None = None
     decision_type: DecisionType = DecisionType.pending
@@ -20,9 +25,9 @@ class DecisionCreate(BaseModel):
     escalation_note: str | None = None
 
     @model_validator(mode="after")
-    def topic_or_workstream_required(self) -> "DecisionCreate":
-        if self.topic_id is None and self.workstream_id is None:
-            raise ValueError("At least one of topic_id or workstream_id must be set")
+    def topic_or_workplan_required(self) -> "DecisionCreate":
+        if self.topic_id is None and self.workplan_id is None:
+            raise ValueError("At least one of topic_id or workplan_id must be set")
         return self
 
 
@@ -45,11 +50,10 @@ class DecisionUpdate(BaseModel):
     superseded_by: uuid.UUID | None = None
 
 
-class DecisionRead(BaseModel):
+class DecisionRead(OptionalWorkplanIdCompatMixin, BaseModel):
     model_config = ConfigDict(from_attributes=True)
     id: uuid.UUID
     topic_id: uuid.UUID | None = None
-    workstream_id: uuid.UUID | None = None
     title: str
     description: str | None = None
     decision_type: DecisionType
@@ -61,4 +65,4 @@ class DecisionRead(BaseModel):
     escalation_note: str | None = None
     superseded_by: uuid.UUID | None = None
     created_at: datetime
-    updated_at: datetime
+    updated_at: datetime