feat(ollama): add availability check before model operations

Add `ensureOllamaAvailable` function to lib/ollama.ts for checking and waiting for Ollama server health with configurable timeout.

Integrate the check in GET /api/ollama/models route with 3s timeout to prevent UI blocking, and in POST /api/ollama/pull route with 20s timeout to ensure availability before pulling models.

Update ChatContainer to always render ModelDropdown for better UX when no model is selected.

app/api/ollama/models/route.ts

@@ -1,5 +1,5 @@
 import { NextResponse } from "next/server";
-import { listModelsViaSdk, listModelsViaHttp } from "@/lib/ollama";
+import { listModelsViaSdk, listModelsViaHttp, ensureOllamaAvailable } from "@/lib/ollama";
 import {
   estimateCpuVram,
   inferDevice,
@@ -31,6 +31,8 @@ function normalizeModel(model: any): ModelInfo {
 export async function GET() {
   try {
     let models: any[] = [];
+    // Tentar garantir disponibilidade rapidamente (não bloquear longamente a UI)
+    await ensureOllamaAvailable({ timeoutMs: 3000 }).catch(() => {});
     try {
       models = await listModelsViaSdk();
     } catch {

app/api/ollama/pull/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest } from "next/server";
-import { pullModel } from "@/lib/ollama";
+import { pullModel, ensureOllamaAvailable } from "@/lib/ollama";
 
 export const dynamic = "force-dynamic";
 
@@ -14,6 +14,18 @@ export async function POST(req: NextRequest) {
     const stream = new ReadableStream({
       async start(controller) {
         try {
+          // Garantir que o servidor esteja disponível antes do pull
+          const ok = await ensureOllamaAvailable({ timeoutMs: 20000 });
+          if (!ok) {
+            controller.enqueue(
+              new TextEncoder().encode(
+                JSON.stringify({ error: "Ollama indisponível" }) + "\n",
+              ),
+            );
+            controller.close();
+            return;
+          }
+
           const response = await pullModel(model);
 
           for await (const chunk of response) {