add bring your own key support

frontend/src/app/core/models/llm.ts

@@ -1,13 +1,21 @@
 export interface LLMGenerateRequest {
   prompt: string;
   siteId: string;
+  provider: string;
+  apiKey?: string;
+  baseUrl?: string;
+  model?: string;
   references?: Reference[];
 }
 
 export interface LLMRefineRequest {
   prompt: string;
   siteId: string;
+  provider: string;
   currentStructure: SiteStructure;
+  apiKey?: string;
+  baseUrl?: string;
+  model?: string;
   references?: Reference[];
 }
 
@@ -64,3 +72,11 @@ export interface GenerationVersion {
   fullStructure: string;
   createdAt: string;
 }
+
+export interface LLMKeyEntry {
+  configured: boolean;
+  baseUrl?: string;
+  model?: string;
+}
+
+export type LLMKeyStatus = Record<string, LLMKeyEntry>;