chore(DeepResearch): improve fullscreen button style

i18n/en.json

@@ -115,5 +115,7 @@
     "newVersionDescription": "Note: If you are using a self-hosted version, please re-deploy to get new features and bug fixes.",
     "refresh": "Refresh page",
     "dismiss": "Dismiss"
-  }
+  },
+  "fullscreen": "Fullscreen",
+  "exitFullscreen": "Exit fullscreen"
 }

i18n/nl.json

@@ -115,5 +115,7 @@
     "newVersionDescription": "Let op: Als u een zelfgehoste versie gebruikt, implementeer deze dan opnieuw om nieuwe functies en bugfixes te krijgen.",
     "refresh": "Pagina vernieuwen",
     "dismiss": "Afwijzen"
-  }
+  },
+  "exitFullscreen": "Volledig scherm verlaten",
+  "fullscreen": "Volledig scherm"
 }

i18n/zh.json

@@ -115,5 +115,7 @@
     "newVersionDescription": "注：如果您使用的是自部署页面，请使用最新代码重新部署，即可获得最新功能和 bug 修复。",
     "refresh": "刷新",
     "dismiss": "忽略"
-  }
+  },
+  "exitFullscreen": "退出全屏",
+  "fullscreen": "全屏"
 }