fix(i18n): remove dict.chat.sending key from i18n

lib/i18n/dictionaries/en.json

@@ -35,7 +35,6 @@
         "placeholder": "Describe your diagram or upload a file...",
         "send": "Send",
         "stopGeneration": "Stop generation",
-        "sending": "Sending...",
         "sendMessage": "Send message",
         "clearConversation": "Clear conversation",
         "diagramHistory": "Diagram history",

lib/i18n/dictionaries/ja.json

@@ -35,7 +35,6 @@
         "placeholder": "ダイアグラムを説明するか、ファイルをアップロード...",
         "send": "送信",
         "stopGeneration": "生成を停止",
-        "sending": "送信中...",
         "sendMessage": "メッセージを送信",
         "clearConversation": "会話をクリア",
         "diagramHistory": "ダイアグラム履歴",

lib/i18n/dictionaries/zh-Hant.json

@@ -35,7 +35,6 @@
         "placeholder": "描述您的圖表或上傳檔案...",
         "send": "傳送",
         "stopGeneration": "停止產生",
-        "sending": "傳送中...",
         "sendMessage": "傳送訊息",
         "clearConversation": "清除對話",
         "diagramHistory": "圖表歷史",

lib/i18n/dictionaries/zh.json

@@ -35,7 +35,6 @@
         "placeholder": "描述您的图表或上传文件...",
         "send": "发送",
         "stopGeneration": "停止生成",
-        "sending": "发送中...",
         "sendMessage": "发送消息",
         "clearConversation": "清除对话",
         "diagramHistory": "图表历史",