Add back button on ticket and task detail screens

lib/screens/tickets/ticket_detail_screen.dart

@@ -199,7 +199,21 @@ class _TicketDetailScreenState extends ConsumerState<TicketDetailScreen> {
           final detailsCard = Card(
             child: Padding(
               padding: const EdgeInsets.all(20),
-              child: SingleChildScrollView(child: detailsContent),
+              child: SingleChildScrollView(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Align(
+                      alignment: Alignment.topLeft,
+                      child: IconButton(
+                        icon: const Icon(Icons.arrow_back),
+                        onPressed: () => Navigator.of(context).pop(),
+                      ),
+                    ),
+                    detailsContent,
+                  ],
+                ),
+              ),
             ),
           );
 
@@ -437,27 +451,23 @@ class _TicketDetailScreenState extends ConsumerState<TicketDetailScreen> {
             ),
           );
 
-          if (isWide) {
-            return Row(
-              children: [
-                Expanded(flex: 2, child: detailsCard),
-                const SizedBox(width: 16),
-                Expanded(flex: 3, child: messagesCard),
-              ],
-            );
-          }
+          final mainContent = isWide
+              ? Row(
+                  children: [
+                    Expanded(flex: 2, child: detailsCard),
+                    const SizedBox(width: 16),
+                    Expanded(flex: 3, child: messagesCard),
+                  ],
+                )
+              : Column(
+                  children: [
+                    detailsCard,
+                    const SizedBox(height: 12),
+                    Expanded(child: messagesCard),
+                  ],
+                );
 
-          // Mobile: avoid nesting scrollables. detailsCard itself is
-          // scrollable if it grows tall, and the messages area takes the
-          // remaining space so the chat list can always receive touch
-          // gestures and never end up offscreen.
-          return Column(
-            children: [
-              detailsCard,
-              const SizedBox(height: 12),
-              Expanded(child: messagesCard),
-            ],
-          );
+          return mainContent;
         },
       ),
     );