add capability to use default model if a default is provided via api

ollamaClient.js

@@ -1,6 +1,31 @@
 const OLLAMA_API_URL = process.env.OLLAMA_API_URL;
 const OLLAMA_API_KEY = process.env.OLLAMA_API_KEY;
-export const OLLAMA_MODEL = process.env.OLLAMA_MODEL || "gemma3:latest";
+export let OLLAMA_MODEL = process.env.OLLAMA_MODEL || "gemma3:latest";
+
+export async function initializeModel() {
+  if (process.env.OLLAMA_MODEL) return;
+  try {
+    const isOpenWebUI = OLLAMA_API_URL?.includes("/api/chat/completions");
+    const baseUrl = OLLAMA_API_URL?.replace(/\/api\/.*$/, "");
+    const url = isOpenWebUI ? `${baseUrl}/api/v1/models` : `${baseUrl}/api/tags`;
+    const headers = isOpenWebUI && OLLAMA_API_KEY 
+      ? { "Authorization": `Bearer ${OLLAMA_API_KEY}` } 
+      : {};
+    const res = await fetch(url, { headers });
+    if (res.ok) {
+      const data = await res.json();
+      const model = isOpenWebUI 
+        ? data.data?.[0]?.id || data.data?.[0]?.name
+        : data.models?.[0]?.name;
+      if (model) {
+        OLLAMA_MODEL = model;
+        console.log(`Using default model: ${model}`);
+      }
+    }
+  } catch (err) {
+    console.warn(`Could not fetch default model, using: ${OLLAMA_MODEL}`);
+  }
+}
 
 function cleanText(str) {
   return str