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.

tests/vitest.config.js

@@ -16,6 +16,8 @@ export default defineConfig({
     alias: {
       // Resolve open-sse/* imports to the actual local package
       "open-sse": resolve(__dirname, "../open-sse"),
+      // Resolve @/* imports to src directory
+      "@": resolve(__dirname, "../src"),
     },
   },
 });