feat: 支持自定义 Minecraft 窗口标题

全局开关 + 默认标题，实例可覆盖；Win32 重命名窗口。前端设置页同步。

packages/app-lib/src/state/instances/commands/edit_instance.rs

@@ -103,6 +103,12 @@ pub struct InstanceLaunchOverridesPatch {
         skip_serializing_if = "Option::is_none",
         with = "serde_with::rust::double_option"
     )]
+    pub window_title: Option<Option<String>>,
+    #[serde(
+        default,
+        skip_serializing_if = "Option::is_none",
+        with = "serde_with::rust::double_option"
+    )]
     pub launch_preparation_timeout: Option<Option<u64>>,
     pub hooks: Option<Hooks>,
 }
@@ -371,6 +377,9 @@ fn apply_launch_overrides_patch(
     if let Some(game_resolution) = patch.game_resolution {
         overrides.game_resolution = game_resolution;
     }
+    if let Some(window_title) = patch.window_title {
+        overrides.window_title = window_title.filter(|value| !value.trim().is_empty());
+    }
     if let Some(mode) = patch.instance_mode {
         overrides.instance_mode = Some(mode);
     }