Implement comprehensive improvement plan (Phases 1-6)

Security (Phase 1-2):
- Add SecurityHeadersMiddleware with CSP, X-Frame-Options, etc.
- Add RateLimitMiddleware for API rate limiting
- Add security event logging to AuditLogModel
- Add ResponseHelper for standardized API responses
- Update config.php with security constants

Database (Phase 3):
- Add migration 014 for additional indexes
- Add migration 015 for ticket dependencies
- Add migration 016 for ticket attachments
- Add migration 017 for recurring tickets
- Add migration 018 for custom fields

Features (Phase 4-5):
- Add ticket dependencies with DependencyModel and API
- Add duplicate detection with check_duplicates API
- Add file attachments with AttachmentModel and upload/download APIs
- Add @mentions with autocomplete and highlighting
- Add quick actions on dashboard rows

Collaboration (Phase 5):
- Add mention extraction in CommentModel
- Add mention autocomplete dropdown in ticket.js
- Add mention highlighting CSS styles

Admin & Export (Phase 6):
- Add StatsModel for dashboard widgets
- Add dashboard stats cards (open, critical, unassigned, etc.)
- Add CSV/JSON export via export_tickets API
- Add rich text editor toolbar in markdown.js
- Add RecurringTicketModel with cron job
- Add CustomFieldModel for per-category fields
- Add admin views: RecurringTickets, CustomFields, Workflow,
  Templates, AuditLog, UserActivity
- Add admin APIs: manage_workflows, manage_templates,
  manage_recurring, custom_fields, get_users
- Add admin routes in index.php

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/TicketModel.php

@@ -223,18 +223,6 @@ class TicketModel {
     }
     
     public function updateTicket($ticketData, $updatedBy = null) {
-        // Debug function
-        $debug = function($message, $data = null) {
-            $log_message = date('Y-m-d H:i:s') . " - [Model] " . $message;
-            if ($data !== null) {
-                $log_message .= ": " . (is_string($data) ? $data : json_encode($data));
-            }
-            $log_message .= "\n";
-            file_put_contents('/tmp/api_debug.log', $log_message, FILE_APPEND);
-        };
-
-        $debug("updateTicket called with data", $ticketData);
-
         $sql = "UPDATE tickets SET
                 title = ?,
                 priority = ?,
@@ -246,43 +234,27 @@ class TicketModel {
                 updated_at = NOW()
                 WHERE ticket_id = ?";
 
-        $debug("SQL query", $sql);
-
-        try {
-            $stmt = $this->conn->prepare($sql);
-            if (!$stmt) {
-                $debug("Prepare statement failed", $this->conn->error);
-                return false;
-            }
-
-            $debug("Binding parameters");
-            $stmt->bind_param(
-                "sissssii",
-                $ticketData['title'],
-                $ticketData['priority'],
-                $ticketData['status'],
-                $ticketData['description'],
-                $ticketData['category'],
-                $ticketData['type'],
-                $updatedBy,
-                $ticketData['ticket_id']
-            );
-
-            $debug("Executing statement");
-            $result = $stmt->execute();
-
-            if (!$result) {
-                $debug("Execute failed", $stmt->error);
-                return false;
-            }
-
-            $debug("Update successful");
-            return true;
-        } catch (Exception $e) {
-            $debug("Exception", $e->getMessage());
-            $debug("Stack trace", $e->getTraceAsString());
-            throw $e;
+        $stmt = $this->conn->prepare($sql);
+        if (!$stmt) {
+            return false;
         }
+
+        $stmt->bind_param(
+            "sissssii",
+            $ticketData['title'],
+            $ticketData['priority'],
+            $ticketData['status'],
+            $ticketData['description'],
+            $ticketData['category'],
+            $ticketData['type'],
+            $updatedBy,
+            $ticketData['ticket_id']
+        );
+
+        $result = $stmt->execute();
+        $stmt->close();
+
+        return $result;
     }
     
     public function createTicket($ticketData, $createdBy = null) {