Paginate attachment listing (#100)

AttachmentModel::getAttachments() had no LIMIT/OFFSET, so a ticket
with hundreds of attachments loaded and rendered every one of them in
a single API response and DOM grid, unbounded.

Added optional limit/offset to getAttachments(), matching the pattern
already used by CommentModel::getCommentsByTicketId(). The GET handler
in upload_attachment.php now accepts limit/offset (default 40, capped
at 100) and returns total/has_more alongside the page of attachments.
ticket.js's loadAttachments()/renderAttachments() now fetch and append
pages, showing a "Load more attachments (N remaining)" control when
more are available. Verified against real MariaDB with 12 attachments
across 3 pages of 5: no duplicates or gaps across pages, and the
legacy unlimited call (getAttachments($ticketId) with no
limit/offset) still returns everything unchanged.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015nCxwFFsy8ouMWzn56rPVP

api/upload_attachment.php

@@ -114,6 +114,9 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
         ResponseHelper::error('Invalid ticket ID format');
     }
 
+    $offset = isset($_GET['offset']) ? max(0, (int)$_GET['offset']) : 0;
+    $limit  = isset($_GET['limit'])  ? min(100, max(1, (int)$_GET['limit'])) : 40;
+
     try {
         $conn = Database::getConnection();
         $ticketModel = new TicketModel($conn);
@@ -123,7 +126,8 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
         }
 
         $attachmentModel = new AttachmentModel($conn);
-        $attachments = $attachmentModel->getAttachments($ticketId);
+        $total = $attachmentModel->getAttachmentCount($ticketId);
+        $attachments = $attachmentModel->getAttachments($ticketId, $limit, $offset);
 
         // Add formatted file size and icon to each attachment
         foreach ($attachments as &$att) {
@@ -131,7 +135,13 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
             $att['icon'] = AttachmentModel::getFileIcon($att['mime_type']);
         }
 
-        ResponseHelper::success(['attachments' => $attachments]);
+        ResponseHelper::success([
+            'attachments' => $attachments,
+            'total'       => $total,
+            'offset'      => $offset,
+            'limit'       => $limit,
+            'has_more'    => ($offset + $limit) < $total,
+        ]);
     } catch (Exception $e) {
         ResponseHelper::serverError('Failed to load attachments');
     }

models/AttachmentModel.php

@@ -16,7 +16,7 @@ class AttachmentModel
     /**
      * Get all attachments for a ticket
      */
-    public function getAttachments($ticketId)
+    public function getAttachments($ticketId, int $limit = 0, int $offset = 0)
     {
         $sql = "SELECT a.*, u.username, u.display_name
                 FROM ticket_attachments a
@@ -24,8 +24,16 @@ class AttachmentModel
                 WHERE a.ticket_id = ?
                 ORDER BY a.uploaded_at DESC";
 
+        if ($limit > 0) {
+            $sql .= " LIMIT ? OFFSET ?";
+        }
+
         $stmt = $this->conn->prepare($sql);
+        if ($limit > 0) {
+            $stmt->bind_param("sii", $ticketId, $limit, $offset);
+        } else {
             $stmt->bind_param("s", $ticketId);
+        }
         $stmt->execute();
         $result = $stmt->get_result();