fix some uploading flyer issues + more unit tests

src/services/aiService.server.ts

@@ -109,7 +109,10 @@ export class AIService {
   private fs: IFileSystem;
   private rateLimiter: <T>(fn: () => Promise<T>) => Promise<T>;
   private logger: Logger;
-  private readonly models = ['gemini-2.5-flash', 'gemini-3-flash', 'gemini-2.5-flash-lite'];
+  // The fallback list is ordered by preference (speed/cost vs. power).
+  // We try the fastest models first, then the more powerful 'pro' model as a high-quality fallback,
+  // and finally the 'lite' model as a last resort.
+  private readonly models = [ 'gemini-3-flash-preview', 'gemini-2.5-flash', 'gemini-2.5-flash-lite'];
 
   constructor(logger: Logger, aiClient?: IAiClient, fs?: IFileSystem) {
     this.logger = logger;
@@ -230,7 +233,8 @@ export class AIService {
           errorMessage.includes('quota') ||
           errorMessage.includes('429') || // HTTP 429 Too Many Requests
           errorMessage.includes('resource_exhausted') || // Make case-insensitive
-          errorMessage.includes('model is overloaded')
+          errorMessage.includes('model is overloaded') ||
+          errorMessage.includes('not found') // Also retry if model is not found (e.g., regional availability or API version issue)
         ) {
           this.logger.warn(
             `[AIService Adapter] Model '${modelName}' failed due to quota/rate limit. Trying next model. Error: ${errorMessage}`,