界面：三维显示设置对话框的关闭按钮说中文（Qt 自带翻译没有被安装）

- What: `Scene3dSettingsDialog.retranslate()` 把 `QDialogButtonBox` 的 Close 按钮文字设为
  `t("dialog.close")`；两个 locale 各加一个 close 键。
- Why: 应用没有安装 Qt 自带的翻译文件，于是按钮框在满屏中文里显示一个英文 Close；对话框是这个
  面板唯一的出口按钮，不该是外来语。
- Verification: `.repro/locale_check.py` 0 缺失（新键双语齐备）；对话框截图目视确认
  （266x531，结尾按钮为「关闭」）。
- Not in this change: 不动其它对话框（它们用自己的按钮，本来就有中文文案）。

apps/studio/config/locales/en_US.json

@@ -78,7 +78,8 @@
     "filter_nyquist": "Note: a {cutoff} Hz cutoff is at or above the Nyquist frequency of {nyquist} Hz (sample rate {rate} Hz) — the device would not filter. Lower the cutoff or pin a higher sample rate.",
     "filter_off": "Not filtering (raw readings)",
     "ok": "OK",
-    "cancel": "Cancel"
+    "cancel": "Cancel",
+    "close": "Close"
   },
   "toolbar": {
     "search_cameras": "Search",

apps/studio/config/locales/zh_CN.json

@@ -78,7 +78,8 @@
     "filter_nyquist": "注意：低通 {cutoff} Hz 已达到或超过奈奎斯特频率 {nyquist} Hz（采样率 {rate} Hz）——设备不会滤。请调低截止频率或固定更高的采样率。",
     "filter_off": "当前不滤波（原始读数）",
     "ok": "确定",
-    "cancel": "取消"
+    "cancel": "取消",
+    "close": "关闭"
   },
   "toolbar": {
     "search_cameras": "搜索",

apps/studio/src/orisys_studio/scene3d/settings_dialog.py

@@ -70,6 +70,11 @@ class Scene3dSettingsDialog(QDialog):
     def retranslate(self) -> None:
         self.setWindowTitle(t("scene3d.settings_title"))
         self.hint.setText(t("scene3d.settings_hint"))
+        # Qt ships its own translations for a button box, and the application installs
+        # none: without this the dialog ends in an English "Close" among Chinese labels.
+        close_button = self.buttons.button(QDialogButtonBox.Close)
+        if close_button is not None:
+            close_button.setText(t("dialog.close"))
 
     # ------------------------------------------------------------------ Qt events
     def closeEvent(self, event) -> None:  # noqa: N802 - Qt naming