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>

cron/create_recurring_tickets.php

@@ -0,0 +1,135 @@
+#!/usr/bin/env php
+<?php
+/**
+ * Recurring Tickets Cron Job
+ *
+ * Run this script via cron to automatically create tickets from recurring schedules.
+ * Recommended: Run every 5-15 minutes
+ *
+ * Example crontab entry:
+ * */10 * * * * /usr/bin/php /path/to/cron/create_recurring_tickets.php >> /var/log/recurring_tickets.log 2>&1
+ */
+
+// Change to project root directory
+chdir(dirname(__DIR__));
+
+// Include required files
+require_once 'config/config.php';
+require_once 'models/RecurringTicketModel.php';
+require_once 'models/TicketModel.php';
+require_once 'models/AuditLogModel.php';
+
+// Log function
+function logMessage($message) {
+    echo "[" . date('Y-m-d H:i:s') . "] " . $message . "\n";
+}
+
+logMessage("Starting recurring tickets cron job");
+
+try {
+    // Create database connection
+    $conn = new mysqli(
+        $GLOBALS['config']['DB_HOST'],
+        $GLOBALS['config']['DB_USER'],
+        $GLOBALS['config']['DB_PASS'],
+        $GLOBALS['config']['DB_NAME']
+    );
+
+    if ($conn->connect_error) {
+        throw new Exception("Database connection failed: " . $conn->connect_error);
+    }
+
+    // Initialize models
+    $recurringModel = new RecurringTicketModel($conn);
+    $ticketModel = new TicketModel($conn);
+    $auditLog = new AuditLogModel($conn);
+
+    // Get all due recurring tickets
+    $dueTickets = $recurringModel->getDueRecurringTickets();
+    logMessage("Found " . count($dueTickets) . " recurring tickets due for creation");
+
+    $created = 0;
+    $errors = 0;
+
+    foreach ($dueTickets as $recurring) {
+        logMessage("Processing recurring ticket ID: " . $recurring['recurring_id']);
+
+        try {
+            // Prepare ticket data
+            $ticketData = [
+                'title' => processTemplate($recurring['title_template']),
+                'description' => processTemplate($recurring['description_template']),
+                'category' => $recurring['category'],
+                'type' => $recurring['type'],
+                'priority' => $recurring['priority'],
+                'status' => 'Open'
+            ];
+
+            // Create the ticket
+            $result = $ticketModel->createTicket($ticketData, $recurring['created_by']);
+
+            if ($result['success']) {
+                $ticketId = $result['ticket_id'];
+                logMessage("Created ticket: " . $ticketId);
+
+                // Assign to user if specified
+                if ($recurring['assigned_to']) {
+                    $ticketModel->updateTicket($ticketId, ['assigned_to' => $recurring['assigned_to']]);
+                }
+
+                // Log to audit
+                $auditLog->log(
+                    $recurring['created_by'],
+                    'create',
+                    'ticket',
+                    $ticketId,
+                    ['source' => 'recurring', 'recurring_id' => $recurring['recurring_id']]
+                );
+
+                // Update the recurring ticket's next run time
+                $recurringModel->updateAfterRun($recurring['recurring_id']);
+
+                $created++;
+            } else {
+                logMessage("ERROR: Failed to create ticket - " . ($result['error'] ?? 'Unknown error'));
+                $errors++;
+            }
+
+        } catch (Exception $e) {
+            logMessage("ERROR: Exception processing recurring ticket - " . $e->getMessage());
+            $errors++;
+        }
+    }
+
+    logMessage("Completed: Created $created tickets, $errors errors");
+
+    $conn->close();
+
+} catch (Exception $e) {
+    logMessage("FATAL ERROR: " . $e->getMessage());
+    exit(1);
+}
+
+/**
+ * Process template variables
+ */
+function processTemplate($template) {
+    if (empty($template)) {
+        return $template;
+    }
+
+    $replacements = [
+        '{{date}}' => date('Y-m-d'),
+        '{{time}}' => date('H:i:s'),
+        '{{datetime}}' => date('Y-m-d H:i:s'),
+        '{{week}}' => date('W'),
+        '{{month}}' => date('F'),
+        '{{year}}' => date('Y'),
+        '{{day_of_week}}' => date('l'),
+        '{{day}}' => date('d'),
+    ];
+
+    return str_replace(array_keys($replacements), array_values($replacements), $template);
+}
+
+logMessage("Cron job finished");