Set up Core Hub framework planning

docs/specs/data-model.md

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+# Data Model Spec
+
+## Purpose
+
+Define the initial Core Hub entity model and the migration stance from State Hub and Inter-Hub.
+
+## Initial Entity Families
+
+Coordination:
+
+- repositories
+- workstreams
+- workplans
+- tasks
+- progress events
+- messages
+- decisions
+
+Framework:
+
+- hubs
+- hub capability manifests
+- API consumers
+- API keys or key references
+- widgets
+- widget types
+- interaction events
+- annotations and annotation threads
+- requirements
+- decision records
+- deployment records
+- outcome signals
+- policy scopes
+- registry facts
+
+Operations:
+
+- request logs
+- auth audit metadata
+- migration batches
+- compatibility fixtures
+- import/export runs
+
+## Migration Posture
+
+- Import Inter-Hub schema facts through explicit migrations or import tools, not ad hoc SQL editing.
+- Preserve identifiers where consumers or historical references depend on them.
+- Treat API key full values as non-recoverable unless an approved custody path says otherwise.
+- Store only hashes, prefixes, labels, and non-secret lifecycle metadata.
+- Record row counts, relationship checks, and fixture replays for every migration batch.
+
+## Open Questions
+
+- Whether Core Hub owns the canonical workplan task tables or continues reading from State Hub until cutover.
+- Whether Inter-Hub admin-only entities should be migrated as historical records or redesigned as Core Hub-native resources.