feat: add sonatype fields (CM-1308)

backend/src/osspckgs/migrations/V1783123200__sonatype_popularity.sql

@@ -0,0 +1,12 @@
+-- Sonatype popularity signal (first delivery: Maven P0, top 500 components).
+-- Sonatype could not provide raw Maven download counts, so instead they deliver a
+-- popularity score derived from their SCA telemetry: normalized 0-100 per ecosystem,
+-- tiered P0-P3. Stored in dedicated columns (not JSONB) because score/rank/tier are
+-- queried independently. Only sonatype_popularity_score feeds rank_packages(); rank and
+-- tier are kept for display/audit. No index on first pass (dataset is small, 500-2k rows).
+ALTER TABLE packages
+    ADD COLUMN IF NOT EXISTS sonatype_popularity_score numeric,      -- 0-100, normalized per ecosystem; consumed by rank_packages()
+    ADD COLUMN IF NOT EXISTS sonatype_rank              int,         -- rank within the Sonatype list; display/audit only
+    ADD COLUMN IF NOT EXISTS sonatype_tier              text,        -- 'P0' | 'P1' | 'P2' | 'P3'
+    ADD COLUMN IF NOT EXISTS sonatype_snapshot_at       timestamptz, -- timestamp of the Sonatype snapshot the row came from
+    ADD COLUMN IF NOT EXISTS sonatype_updated_at        timestamptz; -- our last upsert of the sonatype_* fields