路线地图/节点卡片/详情按出行方式显示不同图标（批 19）

出行方式（飞机/火车/游船/自驾/地铁…）原本在路线地图标记、节点卡片交通行、
节点详情「出行方式」行一律显示节点类型图标（赶路节点恒为 🚗），易让人误解。

- TravelModeController 新增 MODE_ICONS（mode_type → emoji 映射）
- ActivityController::show() 两路查询 LEFT JOIN travel_modes 取 mode_type，注入 modeIcons
- 路线地图标记 / 卡片交通行 / 详情出行方式行：优先用出行方式图标，
  未选出行方式时回退节点类型图标

src/Controllers/ActivityController.php

@@ -314,18 +314,22 @@ class ActivityController
             exit('活动不存在');
         }
 
-        $stmt = $db->prepare('SELECT tn.*, nt.name AS node_type_name, nt.icon AS node_type_icon
+        $stmt = $db->prepare('SELECT tn.*, nt.name AS node_type_name, nt.icon AS node_type_icon,
+                tm.mode_type AS travel_mode_type
             FROM trip_nodes tn
             LEFT JOIN node_types nt ON nt.id = tn.node_type_id
+            LEFT JOIN travel_modes tm ON tm.id = tn.travel_mode_id
             WHERE tn.activity_id = ? AND tn.node_category = "plan"
             ORDER BY tn.start_time ASC');
         $stmt->execute([$id]);
         $planNodes = $stmt->fetchAll();
         $this->attachCounts($db, $planNodes);
 
-        $stmt = $db->prepare('SELECT tn.*, nt.name AS node_type_name, nt.icon AS node_type_icon
+        $stmt = $db->prepare('SELECT tn.*, nt.name AS node_type_name, nt.icon AS node_type_icon,
+                tm.mode_type AS travel_mode_type
             FROM trip_nodes tn
             LEFT JOIN node_types nt ON nt.id = tn.node_type_id
+            LEFT JOIN travel_modes tm ON tm.id = tn.travel_mode_id
             WHERE tn.activity_id = ? AND tn.node_category = "reality"
             ORDER BY tn.start_time ASC');
         $stmt->execute([$id]);
@@ -352,6 +356,8 @@ class ActivityController
             'nodeMembers'     => $nodeMembers,
             // 路线地图：每个执行节点第一张图片附件 id（圆形标记用），一条 GROUP BY 防止 N+1
             'nodeFirstImage'  => Attachments::firstImageIdsForNodes(array_column($realityNodes, 'id')),
+            // 批 19：路线地图标记图标按出行方式映射（回退节点类型图标）
+            'modeIcons'       => TravelModeController::MODE_ICONS,
             'expenseSummary'  => Expenses::summaryForActivity($id),
             'commentTree'     => Comments::tree(Comments::TARGET_ACTIVITY, $id),
             'pageTitle'       => $activity['title'],