feat: add OpenCode Go provider and support for custom models

- Introduced OpenCode Go provider with relevant configurations.
- Enhanced model management by allowing users to add and delete custom models.
- Updated UI components to support model selection for image types.
- Adjusted sidebar visibility to include image media kinds.

src/models/index.js

@@ -25,6 +25,9 @@ export {
   getModelAliases,
   setModelAlias,
   deleteModelAlias,
+  getCustomModels,
+  addCustomModel,
+  deleteCustomModel,
   getMitmAlias,
   setMitmAliasAll,
   getApiKeys,