feat(coding-agent): add provider display names

closes #3956

packages/coding-agent/src/core/extensions/types.ts

@@ -1302,6 +1302,8 @@ export interface ExtensionAPI {
 
 /** Configuration for registering a provider via pi.registerProvider(). */
 export interface ProviderConfig {
+	/** Display name for the provider in UI. */
+	name?: string;
 	/** Base URL for the API endpoint. Required when defining models. */
 	baseUrl?: string;
 	/** API key or environment variable name. Required when defining models (unless oauth provided). */