Fix assigned_to=me filter not working from command palette

The command palette 'My Open Tickets' action navigates to
?assigned_to=me, but DashboardController only handled numeric IDs
and 'unassigned', silently ignoring 'me'. Resolve 'me' to the
current user's ID. Also update the active filter chip to display
'Me' instead of 'User #me'.

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

controllers/DashboardController.php

@@ -142,10 +142,12 @@ class DashboardController {
         $createdBy = $this->validateUserId($_GET['created_by'] ?? null);
         if ($createdBy !== null) $filters['created_by'] = $createdBy;
 
-        // assigned_to accepts a numeric user ID or the special string 'unassigned'
+        // assigned_to accepts a numeric user ID, 'unassigned', or the special string 'me'
         $assignedToRaw = $_GET['assigned_to'] ?? null;
         if ($assignedToRaw === 'unassigned') {
             $filters['assigned_to'] = 'unassigned';
+        } elseif ($assignedToRaw === 'me' && $userId) {
+            $filters['assigned_to'] = (int)$userId;
         } else {
             $assignedTo = $this->validateUserId($assignedToRaw);
             if ($assignedTo !== null) $filters['assigned_to'] = $assignedTo;