Add Activity Timeline feature and database migrations

- Add Activity Timeline tab to ticket view showing chronological history
- Create getTicketTimeline() method in AuditLogModel
- Update TicketController to load timeline data
- Add timeline UI with helper functions for formatting events
- Add comprehensive timeline CSS with dark mode support
- Create migrations 007-010 for upcoming features:
  - 007: Ticket assignment functionality
  - 008: Status workflow transitions
  - 009: Ticket templates
  - 010: Bulk operations tracking

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

assets/css/ticket.css

@@ -441,4 +441,78 @@ input:checked + .slider:before {
 
 .back-btn:hover {
     background: var(--border-color);
+}
+
+/* Activity Timeline Styles */
+.timeline-container {
+    padding: 1rem;
+    max-width: 800px;
+}
+
+.timeline-event {
+    display: flex;
+    gap: 1rem;
+    margin-bottom: 1.5rem;
+    position: relative;
+}
+
+.timeline-event:not(:last-child)::before {
+    content: '';
+    position: absolute;
+    left: 12px;
+    top: 30px;
+    bottom: -24px;
+    width: 2px;
+    background: var(--border-color, #ddd);
+}
+
+.timeline-icon {
+    font-size: 1.5rem;
+    flex-shrink: 0;
+    width: 24px;
+    height: 24px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.timeline-content {
+    flex: 1;
+    background: var(--card-bg, #f8f9fa);
+    padding: 0.75rem 1rem;
+    border-radius: 8px;
+    border: 1px solid var(--border-color, #ddd);
+}
+
+.timeline-header {
+    display: flex;
+    gap: 0.5rem;
+    align-items: center;
+    margin-bottom: 0.5rem;
+    flex-wrap: wrap;
+}
+
+.timeline-action {
+    color: var(--text-muted, #666);
+    font-size: 0.9rem;
+}
+
+.timeline-date {
+    margin-left: auto;
+    color: var(--text-muted, #999);
+    font-size: 0.85rem;
+}
+
+.timeline-details {
+    font-size: 0.9rem;
+    color: var(--text-secondary, #555);
+    padding-top: 0.5rem;
+    border-top: 1px solid var(--border-color, #eee);
+}
+
+body.dark-mode .timeline-content {
+    --card-bg: #2d3748;
+    --border-color: #444;
+    --text-muted: #a0aec0;
+    --text-secondary: #cbd5e0;
 }