fix(catalog-backend): scope pg_class lookups to relkind='i' in migration helpers

Prevents a false match if any non-index object (table, sequence, view)
shares a name with one of the search indices.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

plugins/catalog-backend/migrations/20260510000000_search_indices_and_dedup.js

@@ -188,7 +188,7 @@ async function ensurePgIndex(knex, opts) {
     SELECT indisunique, indisvalid
     FROM pg_index
     WHERE indexrelid = (
-      SELECT oid FROM pg_class WHERE relname = ?
+      SELECT oid FROM pg_class WHERE relname = ? AND relkind = 'i'
     )
   `,
     [name],
@@ -217,7 +217,7 @@ async function ensurePgIndex(knex, opts) {
 async function dropPgIndexIfExists(knex, name) {
   const result = await knex.raw(
     `
-    SELECT 1 FROM pg_class WHERE relname = ?
+    SELECT 1 FROM pg_class WHERE relname = ? AND relkind = 'i'
   `,
     [name],
   );