Preserve usage provider identity

crates/aether-data/migrations/sqlite/20260520010000_preserve_usage_provider_identity.sql

@@ -0,0 +1,18 @@
+-- Usage is a historical fact table. Backfill nullable provider_id snapshots
+-- from the unique provider name where the catalog row still exists.
+
+UPDATE "usage"
+SET provider_id = (
+  SELECT providers.id
+  FROM providers
+  WHERE providers.name = TRIM("usage".provider_name)
+  LIMIT 1
+)
+WHERE provider_id IS NULL
+  AND TRIM(COALESCE(provider_name, '')) <> ''
+  AND LOWER(TRIM(COALESCE(provider_name, ''))) NOT IN ('unknown', 'unknow', 'pending')
+  AND EXISTS (
+    SELECT 1
+    FROM providers
+    WHERE providers.name = TRIM("usage".provider_name)
+  );