feat(launch): M157 实例级启动参数（五项回落 + graphicsBackend 三态）

core: 新增 game/launch_overrides（LaunchOverrides 五项 All-Option + 三级回落 + 文本补丁校验）与 launch/overrides（拼装落位：全局 java.extra_args 进 user.jvm、实例 jvmArgs 进 override_jvm、gameArgs 进 user.game、memory 进 -Xmx、backend 进 --graphicsBackend 并复用既有版本门槛告警）；实例 schema 登记 launch.* 五键。

presenter: dto/LaunchArgsView+LaunchArgsPatch，主机侧读/写与门槛判定（backend_allowed），AppCommand::SetInstanceLaunchArgs。

cli: 新命令 instances launch-args（读/写/--clear），launch 装配链消费回落值。

app-iced: 实例详情页「启动参数」区（JVM/游戏参数、内存、Java、三态后端 chips + 灰化提示 + 保存/恢复），表单状态归 App、i18n 中英文案同步。

crates/app-iced/src/pages/instances.rs

@@ -48,6 +48,8 @@
 mod data;
 mod demo;
 mod detail;
+mod launch_args;
+mod state;
 mod text;
 
 #[cfg(test)]
@@ -55,7 +57,8 @@ mod tests;
 
 #[cfg(test)]
 pub(crate) use data::{DEMO, NOTE, SELECTED};
-pub(super) use demo::demo;
+pub(crate) use demo::{demo, demo_form};
+pub use state::{LaunchForm, Message as InstanceMessage};
 pub(super) use text::Texts;
 
 use iced::widget::{column, container, row, scrollable};
@@ -97,7 +100,12 @@ pub(super) const LIST_BOTTOM_INSET: Space = Space::X2;
 ///
 /// 文案全部走 [`Texts`]（`model.lang` 的语言）：这个函数是实例页唯一的取词入口，
 /// 页面里不留任何可见英文字面量（守门见 `instances/tests/i18n.rs`）。
-pub fn view<'a>(ui: &'a Ui, metrics: FrameMetrics, model: &'a Model) -> Element<'a, Message> {
+pub fn view<'a>(
+    ui: &'a Ui,
+    metrics: FrameMetrics,
+    model: &'a Model,
+    form: &'a LaunchForm,
+) -> Element<'a, Message> {
     let block = &model.instances;
     let forced = model.forced;
     let texts = Texts::of(model.lang.catalog());
@@ -123,12 +131,12 @@ pub fn view<'a>(ui: &'a Ui, metrics: FrameMetrics, model: &'a Model) -> Element<
             metrics,
             list_column(ui, block, forced, texts),
             match &block.detail {
-                Some(detail) => detail::detail_column(ui, metrics, detail, forced, texts),
+                Some(detail) => detail::detail_column(ui, metrics, detail, form, forced, texts),
                 None => detail::detail_empty(ui, texts),
             },
         ),
         _ => match &block.detail {
-            Some(detail) => detail::narrow_detail(ui, metrics, detail, forced, texts),
+            Some(detail) => detail::narrow_detail(ui, metrics, detail, form, forced, texts),
             None => frame::body(metrics, detail::detail_empty(ui, texts)),
         },
     };