fix(openrouter): respect the requesting user's saved model config

generatePostText ignored the userId it received and always read an
arbitrary row via getAnyOpenrouterConfig() (LIMIT 1, no ORDER BY),
so a model chosen and saved in Settings could be shadowed by another
stale config row. Now it prefers the requesting user's own config,
falling back to the most recently updated shared one. Also swap the
retired anthropic/claude-3.5-sonnet default for a live OpenRouter slug.

server/services/openrouter.ts

@@ -18,8 +18,9 @@ export class OpenRouterService {
   private baseUrl = "https://openrouter.ai/api/v1/chat/completions";
 
   async generatePostText(productInfo: ProductInfo, userId: string, modelOverride?: string): Promise<GeneratedText[]> {
-    // Get any available OpenRouter configuration (shared across all users)
-    const config = await storage.getAnyOpenrouterConfig();
+    // Prefer the requesting user's own configuration; fall back to the most
+    // recently saved shared configuration if this user hasn't set one up.
+    const config = (await storage.getOpenrouterConfig(userId)) || (await storage.getAnyOpenrouterConfig());
     
     if (!config) {
       throw new Error('Configuration OpenRouter non trouvée. Veuillez demander à un administrateur de configurer OpenRouter dans les Paramètres.');