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/i18n/locales/en.json

@@ -489,7 +489,10 @@
     "extraOptionValue": "Value",
     "extraOptionKeyPlaceholder": "timeout",
     "extraOptionValuePlaceholder": "600000",
-    "noExtraOptions": "No extra options configured"
+    "noExtraOptions": "No extra options configured",
+    "noModelOptions": "Model options, click + to add",
+    "modelOptionKeyPlaceholder": "provider",
+    "modelOptionValuePlaceholder": "{\"order\": [\"baseten\"]}"
   },
   "providerPreset": {
     "label": "Provider Preset",

src/i18n/locales/ja.json

@@ -489,7 +489,10 @@
     "extraOptionValue": "値",
     "extraOptionKeyPlaceholder": "timeout",
     "extraOptionValuePlaceholder": "600000",
-    "noExtraOptions": "追加オプションはありません"
+    "noExtraOptions": "追加オプションはありません",
+    "noModelOptions": "モデルオプション、+ をクリックして追加",
+    "modelOptionKeyPlaceholder": "provider",
+    "modelOptionValuePlaceholder": "{\"order\": [\"baseten\"]}"
   },
   "providerPreset": {
     "label": "プロバイダータイプ",

src/i18n/locales/zh.json

@@ -489,7 +489,10 @@
     "extraOptionValue": "值",
     "extraOptionKeyPlaceholder": "timeout",
     "extraOptionValuePlaceholder": "600000",
-    "noExtraOptions": "暂无额外选项"
+    "noExtraOptions": "暂无额外选项",
+    "noModelOptions": "模型选项，点击 + 添加",
+    "modelOptionKeyPlaceholder": "provider",
+    "modelOptionValuePlaceholder": "{\"order\": [\"baseten\"]}"
   },
   "providerPreset": {
     "label": "预设供应商",