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>

views/CreateTicketView.php

@@ -105,6 +105,13 @@
                         <label for="title">Ticket Title *</label>
                         <input type="text" id="title" name="title" class="editable" required placeholder="Enter a descriptive title for this ticket">
                     </div>
+                    <!-- Duplicate Warning Area -->
+                    <div id="duplicateWarning" style="display: none; margin-top: 1rem; padding: 1rem; border: 2px solid var(--terminal-amber); background: rgba(241, 196, 15, 0.1);">
+                        <div style="color: var(--terminal-amber); font-weight: bold; margin-bottom: 0.5rem;">
+                            Possible Duplicates Found
+                        </div>
+                        <div id="duplicatesList"></div>
+                    </div>
                 </div>
             </div>
 
@@ -187,5 +194,63 @@
         </form>
     </div>
     <!-- END OUTER FRAME -->
+
+    <script>
+    // Duplicate detection with debounce
+    let duplicateCheckTimeout = null;
+
+    document.getElementById('title').addEventListener('input', function() {
+        clearTimeout(duplicateCheckTimeout);
+        const title = this.value.trim();
+
+        if (title.length < 5) {
+            document.getElementById('duplicateWarning').style.display = 'none';
+            return;
+        }
+
+        // Debounce: wait 500ms after user stops typing
+        duplicateCheckTimeout = setTimeout(() => {
+            checkForDuplicates(title);
+        }, 500);
+    });
+
+    function checkForDuplicates(title) {
+        fetch('/api/check_duplicates.php?title=' + encodeURIComponent(title))
+            .then(response => response.json())
+            .then(data => {
+                const warningDiv = document.getElementById('duplicateWarning');
+                const listDiv = document.getElementById('duplicatesList');
+
+                if (data.success && data.duplicates && data.duplicates.length > 0) {
+                    let html = '<ul style="margin: 0; padding-left: 1.5rem; color: var(--terminal-green);">';
+                    data.duplicates.forEach(dup => {
+                        html += `<li style="margin-bottom: 0.5rem;">
+                            <a href="/ticket/${escapeHtml(dup.ticket_id)}" target="_blank" style="color: var(--terminal-green);">
+                                #${escapeHtml(dup.ticket_id)}
+                            </a>
+                            - ${escapeHtml(dup.title)}
+                            <span style="color: var(--terminal-amber);">(${dup.similarity}% match, ${escapeHtml(dup.status)})</span>
+                        </li>`;
+                    });
+                    html += '</ul>';
+                    html += '<p style="margin-top: 0.5rem; font-size: 0.85rem; color: var(--terminal-green-dim);">Consider checking these tickets before creating a new one.</p>';
+
+                    listDiv.innerHTML = html;
+                    warningDiv.style.display = 'block';
+                } else {
+                    warningDiv.style.display = 'none';
+                }
+            })
+            .catch(error => {
+                console.error('Error checking duplicates:', error);
+            });
+    }
+
+    function escapeHtml(text) {
+        const div = document.createElement('div');
+        div.textContent = text;
+        return div.innerHTML;
+    }
+    </script>
 </body>
 </html>