fix(workers): skip background jobs when required tables are missing

Backend/utils/db-schema.ts

@@ -0,0 +1,24 @@
+import { pool } from '../db/client';
+
+const PUBLIC_SCHEMA = 'public';
+
+export const tableExists = async (tableName: string): Promise<boolean> => {
+  const result = await pool.query<{ exists: boolean }>(
+    `
+      select exists (
+        select 1
+        from information_schema.tables
+        where table_schema = $1
+          and table_name = $2
+      ) as "exists"
+    `,
+    [PUBLIC_SCHEMA, tableName],
+  );
+
+  return result.rows[0]?.exists === true;
+};
+
+export const hasRequiredTables = async (tableNames: string[]): Promise<boolean> => {
+  const checks = await Promise.all(tableNames.map((tableName) => tableExists(tableName)));
+  return checks.every(Boolean);
+};