feat(opencode): add manual provider key input with duplicate check

- Add Provider Key input field for OpenCode providers (between icon and name)
- User must manually enter a unique key instead of auto-generating from name
- Real-time validation: format check and duplicate detection
- Key is immutable after creation (disabled in edit mode)
- Remove slugify auto-generation logic from mutations
- Add beforeNameSlot prop to BasicFormFields for extensibility
- Add i18n translations for zh/en/ja

src/hooks/useProviderActions.ts

@@ -54,7 +54,7 @@ export function useProviderActions(activeApp: AppId) {
 
   // 添加供应商
   const addProvider = useCallback(
-    async (provider: Omit<Provider, "id">) => {
+    async (provider: Omit<Provider, "id"> & { providerKey?: string }) => {
       await addProviderMutation.mutateAsync(provider);
     },
     [addProviderMutation],