fix: OilReference最后2处@click.self改为@mousedown.self，拖选不误关

全局已无@click.self弹窗关闭，统一使用@mousedown.self。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/views/OilReference.vue

@@ -235,7 +235,7 @@
     </div>
 
     <!-- Simple Oil Detail Panel (for oils without a knowledge card) -->
-    <div v-if="selectedOilName && !activeCard" class="modal-overlay" @click.self="selectedOilName = null">
+    <div v-if="selectedOilName && !activeCard" class="modal-overlay" @mousedown.self="selectedOilName = null">
       <div class="oil-detail-panel">
         <div class="detail-header">
           <div>
@@ -305,7 +305,7 @@
     </div>
 
     <!-- Edit Oil Overlay -->
-    <div v-if="editingOilName" class="modal-overlay" @click.self="editingOilName = null" @keydown.enter="$event.isComposing || saveEditOil()">
+    <div v-if="editingOilName" class="modal-overlay" @mousedown.self="editingOilName = null" @keydown.enter="$event.isComposing || saveEditOil()">
       <div class="modal-panel">
         <div class="modal-header">
           <h3>{{ editingOilName }}</h3>