Enhance command prompts in localization files

- Updated placeholder text in English, Simplified Chinese, and Traditional Chinese to guide users on using commands.
- Added loading and load failed messages for commands in all three languages.

src/locales/en-US.ts

@@ -722,7 +722,9 @@ export default {
     untitledSession: 'Untitled chat',
     emptyTitle: 'What should we handle today?',
     emptySubtitle: 'Ask about sites, subscriptions, downloads, or organization tasks.',
-    placeholder: 'Ask MoviePilot...',
+    placeholder: 'Ask MoviePilot, Type / for commands',
+    commandLoading: 'Loading commands...',
+    commandLoadFailed: 'Failed to load commands',
     stop: 'Stop generating',
     download: 'Download',
     attachFile: 'Choose image or file',

src/locales/zh-CN.ts

@@ -718,7 +718,9 @@ export default {
     untitledSession: '未命名会话',
     emptyTitle: '今天想处理什么？',
     emptySubtitle: '站点、订阅、下载、整理任务，都可以直接问我。',
-    placeholder: '询问 MoviePilot...',
+    placeholder: '询问 MoviePilot，输入 / 使用命令',
+    commandLoading: '正在加载命令...',
+    commandLoadFailed: '命令列表加载失败',
     stop: '停止生成',
     download: '下载',
     attachFile: '选择图片或文件',

src/locales/zh-TW.ts

@@ -718,7 +718,9 @@ export default {
     untitledSession: '未命名會話',
     emptyTitle: '今天想處理什麼？',
     emptySubtitle: '站點、訂閱、下載、整理任務，都可以直接問我。',
-    placeholder: '詢問 MoviePilot...',
+    placeholder: '詢問 MoviePilot，輸入 / 使用命令',
+    commandLoading: '正在載入命令...',
+    commandLoadFailed: '命令列表載入失敗',
     stop: '停止生成',
     download: '下載',
     attachFile: '選擇圖片或文件',