resolve issues with new features

backend/src/database/migrations/024_create_app_settings.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS app_settings (
+  key VARCHAR(100) PRIMARY KEY,
+  value JSONB NOT NULL DEFAULT '{}',
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_by UUID REFERENCES users(id) ON DELETE SET NULL
+);
+
+-- Seed default external links (empty array)
+INSERT INTO app_settings (key, value) VALUES
+  ('external_links', '[]'::jsonb),
+  ('refresh_intervals', '{"dashboard": 300000, "admin_services": 15000}'::jsonb)
+ON CONFLICT (key) DO NOTHING;