Ensure globals.js is loaded prior to execution of dependent scripts

This commit prevents a race condition that causes global variables
defined in globals.js to be inaccessible to the other content scripts

globals.js

@@ -1,16 +1,26 @@
-console.log('globals.js loaded');
+if (typeof window.globalsLoaded === 'undefined') {
+    console.log('globals.js loaded');
 
-let lastChecked = null;
+    window.globalsLoaded = true;
 
-let Selectors = {
-    // Plus 用户的选择器
-    conversationsCheckbox: '.conversation-checkbox:checked',
-    deleteButton: '[class*="text-red"]',
-    confirmDeleteButton: 'button.btn.btn-danger',
-    threeDotButton: '[id^="radix-"]',
-    // 其他 Plus 用户选择器...
-    CONVERSATION_SELECTOR: 'div > div > div > div > div > div > nav > div > div > div > div > ol > li > div > a',
-    TITLE_SELECTOR: '.relative.grow.overflow-hidden.whitespace-nowrap',
-};
+    let lastChecked = null;
 
-let CHECKBOX_CLASS = 'conversation-checkbox';
+    let Selectors = {
+        // Plus 用户的选择器
+        conversationsCheckbox: '.conversation-checkbox:checked',
+        deleteButton: '[class*="text-red"]',
+        confirmDeleteButton: 'button.btn.btn-danger',
+        threeDotButton: '[id^="radix-"]',
+        // 其他 Plus 用户选择器...
+        CONVERSATION_SELECTOR: 'div > div > div > div > div > div > nav > div > div > div > div > ol > li > div > a',
+        TITLE_SELECTOR: '.relative.grow.overflow-hidden.whitespace-nowrap',
+    };
+
+    let CHECKBOX_CLASS = 'conversation-checkbox';
+
+    window.lastChecked = lastChecked;
+    window.Selectors = Selectors;
+    window.CHECKBOX_CLASS = CHECKBOX_CLASS;
+} else {
+    console.log('globals.js already loaded, skipping re-initialization');
+}