Show OpenAI test failure details

public/admin.js

@@ -447,9 +447,19 @@ function openAiTestMessage(result) {
   if (result?.error === "invalid_key") return "OpenAI klic je spatny nebo nema pristup. Vloz novy klic.";
   if (result?.error === "bad_model") return "Zvoleny OpenAI model neni dostupny pro tento klic. Vyber jiny model.";
   if (result?.error === "rate_limited") return "OpenAI docasne omezuje pozadavky. Zkus test za chvili.";
+  if (result?.message) return `Test selhal (${result?.error || "chyba"}): ${shortErrorMessage(result.message)}`;
   return "";
 }
 
+function shortErrorMessage(value) {
+  const text = String(value || "")
+    .replace(/\s+/g, " ")
+    .replace(/^OpenAI HTTP\s+/i, "OpenAI ")
+    .trim();
+  if (!text) return "bez detailu";
+  return text.length > 220 ? `${text.slice(0, 217)}...` : text;
+}
+
 function setOpenAiStatus(message) {
   $("#openaiApiKeyStatus").textContent = message;
 }