Normalize feedback primary key to (id) for upgraded installs

go/core/pkg/migrations/core/000004_feedback_single_pk.down.sql

@@ -0,0 +1,9 @@
+-- No-op: 000004 is a corrective convergence step. Both fresh installs (which
+-- already had PRIMARY KEY (id) from 000001) and upgraded installs (which
+-- carried the legacy composite PRIMARY KEY (id, user_id) from GORM
+-- AutoMigrate) end at PRIMARY KEY (id). Once up has run, there is no way to
+-- tell which path the database came from, so a symmetric down would put fresh
+-- installs into a composite-PK state they never originally had. Leaving the
+-- single-column PK in place on rollback is safer and the application is
+-- PK-shape independent (queries do not reference the PK directly).
+SELECT 1;

go/core/pkg/migrations/core/000004_feedback_single_pk.up.sql

@@ -0,0 +1,13 @@
+-- Normalize the feedback primary key to (id) only.
+--
+-- Fresh installs from 000001 already have PRIMARY KEY (id) (BIGSERIAL).
+-- Installs that upgraded from the GORM-managed schema retained the legacy
+-- composite PRIMARY KEY (id, user_id) created by AutoMigrate.
+--
+-- Both variants use the default constraint name `feedback_pkey`, so this
+-- atomic drop+add converges both paths to the single-column PK without
+-- changing column types or affecting sqlc-generated code (queries do not
+-- reference the PK; ListFeedback filters on user_id via idx_feedback_user_id).
+ALTER TABLE feedback
+    DROP CONSTRAINT feedback_pkey,
+    ADD CONSTRAINT feedback_pkey PRIMARY KEY (id);