feat: ticket watchers, fulltext search, single-query pagination, watcher notifications

Ticket watchers:
- api/watch_ticket.php: GET (watch state) + POST (watch/unwatch toggle)
- index.php: route for /api/watch_ticket.php
- TicketView: WATCH/UNWATCH button with live state fetch and toggle
- NotificationHelper::notifyWatchers(): fetches watchers from DB, resolves
  Matrix IDs via Synapse, fires notification to watchers + global list
- add_comment.php, update_ticket.php: call notifyWatchers on comment and
  status-change events respectively

Fulltext search:
- TicketModel::hasFulltextIndex(): detects FULLTEXT index via information_schema
- getAllTickets(): uses MATCH...AGAINST when fulltext index exists, LIKE fallback
  when not yet applied — zero-downtime rollout

Single-query pagination:
- getAllTickets() replaces separate COUNT + SELECT with COUNT(*) OVER() window
  function — one round trip to DB per page load instead of two

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/update_ticket.php

@@ -54,6 +54,7 @@ try {
 
     // Updated controller class that handles partial updates
     class ApiTicketController {
+        private $conn;
         private $ticketModel;
         private $commentModel;
         private $auditLog;
@@ -63,6 +64,7 @@ try {
         private $currentUser;
 
         public function __construct($conn, $userId = null, $isAdmin = false, $currentUser = []) {
+            $this->conn = $conn;
             $this->ticketModel = new TicketModel($conn);
             $this->commentModel = new CommentModel($conn);
             $this->auditLog = new AuditLogModel($conn);
@@ -208,7 +210,7 @@ try {
                 }
             }
 
-            // Notify on status change
+            // Notify on status change (global notify list + watchers)
             if ($currentTicket['status'] !== $updateData['status']) {
                 $changedBy = $this->currentUser['display_name'] ?? $this->currentUser['username'] ?? null;
                 NotificationHelper::sendStatusChangeNotification(
@@ -218,6 +220,14 @@ try {
                     $updateData['title'],
                     $changedBy
                 );
+                NotificationHelper::notifyWatchers(
+                    $this->conn,
+                    $id,
+                    $updateData['title'],
+                    'status_changed',
+                    ['old_status' => $currentTicket['status'], 'new_status' => $updateData['status'], 'changed_by' => $changedBy],
+                    (int)$this->userId
+                );
             }
 
             return [