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/types.ts

@@ -262,6 +262,7 @@ export interface OpenCodeModel {
     context?: number;
     output?: number;
   };
+  options?: Record<string, unknown>; // 模型级别额外选项（provider 路由等）
 }
 
 // OpenCode 供应商选项