feat(provenance): govern source snapshots and data inputs

docs/DATABASE_IMPLEMENTATION_PLAN.md

@@ -69,6 +69,41 @@ Spatial index required on `geometry`.
 - `status text default 'created'`
 - `created_at timestamptz`
 
+### Source registry, snapshots and quarantine (Accuracy Phase 2)
+
+Migration `202608010001_source_registry_provenance` adds a server-owned
+provenance boundary without deleting or inventing facts for existing rows.
+
+`source_registry` stores one governed source definition per `source_key`:
+
+- classification (`authoritative`, `corroborative`, `contextual`, `derived`,
+  `experimental`), authority/scope and provider adapter key;
+- licence, usage restrictions, expected CRS/units/resolution, temporal and
+  geographic coverage, expected geometry/attributes and known limitations;
+- usage policy, freshness and ingest status.
+
+`source_snapshots` stores immutable acquired editions keyed by
+`(source_registry_id, snapshot_key)`, including source version/snapshot/fetch
+time, lowercase SHA-256 checksum, CRS/units/resolution, coverage, observed
+schema, freshness, ingest status and raw snapshot metadata.
+
+`datasets` and `dataset_versions` receive `source_registry_id`,
+`source_snapshot_id`, data-contract key/version, validation report/status,
+provenance/lineage status and idempotent `ingest_key`. New governed records
+must have a passing report before they become `ready`. Legacy rows are retained
+with explicit incomplete/not-validated state; a migration never promotes them
+based on a historical `source_name` string.
+
+`dataset_lineage_edges` records parent/child Dataset(+Version), transform name
+and version, parameters and input/output hashes. `dataset_quarantines` retains
+the rejected dataset/version/snapshot, stage, reason, validation evidence and
+artifact location. Quarantine is a stateful preservation record, not a delete.
+
+The database constraints enforce accepted status vocabularies, nonblank ingest
+keys, immutable snapshot identity/checksum format, unique ingest idempotency
+keys and non-self lineage edges. Service-level contract validation remains
+responsible for CRS, topology, bbox, units and source-task semantics.
+
 ### vector_features
 
 Used for imported vector datasets and derived vector outputs when feature-level storage is needed. Original files remain source artifacts; this table is the queryable PostGIS state for vector features.