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/models/topic.py

@@ -36,8 +36,8 @@ class Topic(Base, TimestampMixin):
     domain: Mapped["Domain"] = relationship(  # noqa: F821
         "Domain", back_populates="topics", lazy="selectin"
     )
-    workstreams: Mapped[list["Workstream"]] = relationship(  # noqa: F821
-        "Workstream", back_populates="topic", lazy="selectin"
+    workplans: Mapped[list["Workplan"]] = relationship(  # noqa: F821
+        "Workplan", back_populates="topic", lazy="selectin"
     )
     decisions: Mapped[list["Decision"]] = relationship(  # noqa: F821
         "Decision", back_populates="topic", lazy="selectin"