Fix database error in complaint field update - remove non-existent updated_at column

BUGFIX: Database error when saving editable complaint fields

PROBLEM: After adding X-Requested-With header, the request reached
the controller but threw 'Database error' when trying to update the
complaint field.

ROOT CAUSE: The ipd_discharge_complaint table does not have an
'updated_at' column. The update query was trying to set:
  - comp_report or comp_remark (correct)
  - updated_at (does not exist) ← DATABASE ERROR

INVESTIGATION: Checked how complaint rows are inserted elsewhere in
the codebase (line 4117-4130). The table has 'update_by' column for
tracking changes, not 'updated_at'.

SOLUTION:
1. Removed hardcoded 'updated_at' => date(...) from update data
2. Only update the target field (comp_report or comp_remark)
3. Conditionally set 'update_by' if column exists (audit trail)
4. Use session full_name for user tracking

Now editable complaint fields save successfully without database errors.

app/Controllers/Ipd_discharge.php

@@ -2836,12 +2836,16 @@ class Ipd_discharge extends BaseController
         $columnName = $fieldType === 'name' ? 'comp_report' : 'comp_remark';
         
         try {
+            $updateData = [$columnName => $fieldValue];
+            
+            // Only set update_by if column exists
+            if ($this->db->fieldExists('update_by', $table)) {
+                $updateData['update_by'] = $this->session->get('full_name') ?? 'System';
+            }
+
             $updated = $this->db->table($table)
                 ->where('id', $complaintId)
-                ->update([
-                    $columnName => $fieldValue,
-                    'updated_at' => date('Y-m-d H:i:s')
-                ]);
+                ->update($updateData);
 
             if ($updated) {
                 return $this->response->setJSON(['success' => true]);