Fix bugs found in second multi-agent review

XSS / security:
- markdown.js: sanitize footnote labels to a safe slug before using them in
  id/href attributes. Labels are captured before the HTML-escape pass, so a
  label like x"><img onerror=...> broke out → stored XSS (the earlier quote-
  escape fix didn't cover this path). Verified neutralized.
- RateLimitMiddleware: only trust X-Forwarded-For / X-Real-IP when REMOTE_ADDR
  is a configured trusted proxy, and use the rightmost (proxy-appended) entry.
  Previously any client could rotate XFF to escape the per-IP rate limit.
- .env.example: document TRUSTED_PROXIES so fresh deploys aren't fail-open on
  the Authelia forward-auth spoofing protection.

Correctness:
- notifications.php: my previous assigned-to LIKE fix anchored only on '}', so
  BULK assignments (logged {"assigned_to":N,"bulk_operation_id":..}) produced
  no "assigned to you" notification — now matches both '}' and ',' delimiters.
- notifications.php: implement the documented @mention notifications (query
  action_type='mention' rows for the current user); they were never delivered.
- NotificationHelper::notifyWatchers: guard unchecked prepare() so a missing
  ticket_watchers table can't fatal the request after its DB write committed.
- AuditLogModel::getTicketTimeline: JSON_UNQUOTE the extracted ticket_id so
  comment events actually match (string vs JSON-number comparison never did).
- AuditLogModel/audit_log.php: CSV export no longer silently truncates to the
  1000-row UI cap; uses a dedicated higher export limit.
- DashboardView: quick-preview drawer read .ticket-link from the title cell
  (which has none), so the title was always blank — use the cell text.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

api/notifications.php

@@ -55,15 +55,18 @@ $assignSql = "SELECT
     AND al.entity_type = 'ticket'
     AND al.user_id != ?
     AND al.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)
-    AND al.details LIKE ?
+    AND (al.details LIKE ? OR al.details LIKE ?)
   ORDER BY al.created_at DESC
   LIMIT 15";
 
 // Match the exact JSON value with a trailing delimiter so user 12 doesn't also
-// match 120/123/etc. The assign detail is logged as {"assigned_to":<int>}.
-$assignLike = '%"assigned_to":' . (int)$userId . '}%';
+// match 120/123/etc. Single assigns log {"assigned_to":5} (closing brace) while
+// bulk assigns log {"assigned_to":5,"bulk_operation_id":N} (comma) — match both.
+$assignId    = (int)$userId;
+$assignEnd   = '%"assigned_to":' . $assignId . '}%';
+$assignMid   = '%"assigned_to":' . $assignId . ',%';
 $stmt = $conn->prepare($assignSql);
-$stmt->bind_param('is', $userId, $assignLike);
+$stmt->bind_param('iss', $userId, $assignEnd, $assignMid);
 $stmt->execute();
 $assignRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
 $stmt->close();
@@ -150,10 +153,32 @@ $stmt->execute();
 $statusRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
 $stmt->close();
 
+// Query 4: @mentions of me (logged by add_comment.php as
+// action_type='mention', entity_type='user', entity_id=<mentioned user_id>).
+$mentionSql = "SELECT
+    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
+    COALESCE(u.display_name, u.username, 'System') AS actor_name
+  FROM audit_log al
+  LEFT JOIN users u ON al.user_id = u.user_id
+  WHERE al.action_type = 'mention'
+    AND al.entity_type = 'user'
+    AND al.entity_id = ?
+    AND al.user_id != ?
+    AND al.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)
+  ORDER BY al.created_at DESC
+  LIMIT 15";
+
+$mentionEntityId = (string)$userId;
+$stmt = $conn->prepare($mentionSql);
+$stmt->bind_param('si', $mentionEntityId, $userId);
+$stmt->execute();
+$mentionRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
+$stmt->close();
+
 // Merge, deduplicate by log_id, sort by created_at desc
 $all = [];
 $seen = [];
-foreach (array_merge($assignRows, $commentRows, $statusRows) as $row) {
+foreach (array_merge($assignRows, $commentRows, $statusRows, $mentionRows) as $row) {
     $id = (int)$row['log_id'];
     if (isset($seen[$id])) {
         continue;
@@ -172,7 +197,7 @@ foreach ($all as $row) {
     $actionType = ($row['action_type'] === 'create' && $row['entity_type'] === 'comment')
         ? 'comment'
         : $row['action_type'];
-    $ticketId = ($actionType === 'comment')
+    $ticketId = ($actionType === 'comment' || $actionType === 'mention')
         ? ($details['ticket_id'] ?? 0)
         : $row['entity_id'];
     $isRead = $lastSeen && $row['created_at'] <= $lastSeen;
@@ -181,6 +206,7 @@ foreach ($all as $row) {
     $title = match ($actionType) {
         'assign'  => "{$row['actor_name']} assigned ticket #{$ticketId} to you",
         'comment' => "{$row['actor_name']} commented on ticket #{$ticketId}",
+        'mention' => "{$row['actor_name']} mentioned you on ticket #{$ticketId}",
         'update'  => (function () use ($row, $details, $ticketId) {
             // logTicketUpdate stores delta as {"status": {"from": "Open", "to": "In Progress"}}
             $from = $details['status']['from'] ?? ($details['old_value'] ?? '?');