feat(opencode): add model-level options editor

Add support for configuring per-model options like provider routing.
Each model row now has an expand/collapse toggle to show a key-value
editor for model-specific options (e.g., provider order, fallbacks).

- Add options field to OpenCodeModel in Rust and TypeScript
- Add expandable key-value editor UI for each model
- Use local state pattern for option key input to prevent focus loss
- Add i18n translations for zh/en/ja

src-tauri/src/provider.rs

@@ -537,6 +537,10 @@ pub struct OpenCodeModel {
     /// 模型限制（上下文和输出 token 数）
     #[serde(skip_serializing_if = "Option::is_none")]
     pub limit: Option<OpenCodeModelLimit>,
+
+    /// 模型额外选项（provider 路由等）
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub options: Option<HashMap<String, Value>>,
 }
 
 /// OpenCode 模型限制