Add support for pg_stat_statements configuration in Targets

This commit introduces a `use_pg_stat_statements` flag for targets, allowing users to enable or disable the use of `pg_stat_statements` for query insights. It includes database schema changes, backend logic, and UI updates to manage this setting in both creation and editing workflows.

frontend/src/styles.css

@@ -249,6 +249,21 @@ button {
   color: #8fa0bf;
 }
 
+.toggle-check {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  font-size: 14px;
+  color: #d7e6fb;
+  cursor: pointer;
+}
+
+.toggle-check input[type="checkbox"] {
+  width: 16px;
+  height: 16px;
+  accent-color: #27bbf3;
+}
+
 .tips p {
   margin: 8px 0;
   color: #bfd0ea;