Add hub-core package, docs, and State Hub integration scaffold

Extract the first reusable slice (models, schemas, routers, MCP, migrations)
from state-hub with INTENT/SCOPE, agent instructions, workplan, and aligned
inter_hub capability registry index.

README.md

@@ -1,3 +1,36 @@
-# repo-seed
+# Hub Core
 
-A git repository template to bootstrap coulomb projects from.
+Reusable FastAPI, SQLAlchemy, and MCP primitives for FOS hubs.
+
+`hub-core` is being extracted from the standalone State Hub repository as part
+of `CUST-WP-0025`. The initial package slice contains only the generic database
+models and schemas that can move without importing dev-hub concepts such as
+topics, workstreams, tasks, decisions, SBOM, or token accounting.
+
+Source boundary notes live in:
+
+```text
+/home/worsch/the-custodian/docs/hub-core-extraction-boundary.md
+```
+
+## First Slice
+
+- SQLAlchemy base metadata and timestamp helpers.
+- Domain and managed-repository registry primitives.
+- Agent message inbox primitives.
+- Progress-event and capability-request primitives with generic JSON context
+  fields for hub-specific references.
+- Third-party service catalog and snapshot primitives.
+- Matching Pydantic schemas for those primitives.
+- Generic DoI report and summary schemas used by the MCP DoI tools.
+- Router factory functions for domains, repos, messages, policy lookup, and
+  progress, capability, and TPSC catalog/snapshot/report endpoints.
+- Canonical FOS §10 risk and alert event types with `/progress/risks` and
+  `/progress/alerts` read views.
+- Shared utility helpers for slugs, pagination, repo path resolution, and
+  trailing-slash path normalization.
+- Alembic templates plus an initial core-schema migration for hub adopters.
+- FastMCP base-server wrapper for generic orientation, messaging, capability,
+  repo, DoI, TPSC/GDPR, risk/alert, and progress tools.
+
+Domain-specific MCP tools follow in each hub package.