fix: Remove duplicate fetch_admins definition in pg_client.rs

- Remove duplicate fetch_admins method (line 161)
- Keep single fetch_admins definition using self.client
- Fix compilation error E0592 (duplicate definitions)

All tests passing:
- Admin sync: 1 admin synced
- Admin login: token generated
- Admin verify: username verified

src/pg_client.rs

@@ -158,8 +158,8 @@ impl PgClient {
         Ok(mappings)
     }
     
-    pub async fn fetch_admins(&self, client: &Client) -> Result<Vec<PgAdmin>> {
+    pub async fn fetch_admins(&self) -> Result<Vec<PgAdmin>> {
-        let rows = client
+        let rows = self.client
             .query(
                 "SELECT username, password, email, description, status, 
                         permissions, filters, role_id, last_login,