feat: add database support, conversation sidebar, and improve chat streaming

- Update .gitignore to exclude database files, extensions, and .cursor directory
- Enhance chat streaming API with safe enqueue and close functions to prevent errors
- Integrate ConversationSidebar component into ClientHome for better UI
- Add dependencies like better-sqlite3 and esbuild packages for database functionality

This commit introduces database persistence for conversations, improves error handling in streaming responses, and adds a sidebar for managing chats, enhancing overall app robustness and user experience.

lib/ollama.ts

@@ -29,10 +29,11 @@ export async function chatWithStream(
   const client = new Ollama({ host: OLLAMA_HOST });
   return client.chat({
     model,
-    messages,
+    messages: system
+      ? [...messages, { role: "system", content: system }]
+      : messages,
     stream: true,
     options,
-    system,
   });
 }
 
@@ -40,3 +41,62 @@ export async function pullModel(model: string) {
   const client = new Ollama({ host: OLLAMA_HOST });
   return client.pull({ model, stream: true });
 }
+
+export async function checkModelExists(modelName: string): Promise<boolean> {
+  try {
+    const models = await listModelsViaSdk();
+    return models.some((model) => model.name === modelName);
+  } catch (error) {
+    console.error("Erro ao verificar modelos:", error);
+    return false;
+  }
+}
+
+export async function ensureModelExists(
+  modelName: string,
+  description?: string
+): Promise<void> {
+  const exists = await checkModelExists(modelName);
+  if (!exists) {
+    console.log(`📥 Baixando modelo ${modelName}...`);
+    if (description) {
+      console.log(`ℹ️  ${description}`);
+    }
+
+    const stream = await pullModel(modelName);
+    let downloadedBytes = 0;
+    let totalBytes = 0;
+    let progress = 0;
+
+    // Processar stream para mostrar progresso
+    for await (const chunk of stream) {
+      if (chunk.status === "downloading" && chunk.completed && chunk.total) {
+        downloadedBytes = chunk.completed;
+        totalBytes = chunk.total;
+        progress = Math.round((downloadedBytes / totalBytes) * 100);
+
+        // Criar barra de progresso visual
+        const barLength = 20;
+        const filledLength = Math.round((progress / 100) * barLength);
+        const bar =
+          "█".repeat(filledLength) + "░".repeat(barLength - filledLength);
+
+        // Mostrar progresso com informações
+        const downloadedMB = (downloadedBytes / 1024 / 1024).toFixed(1);
+        const totalMB = (totalBytes / 1024 / 1024).toFixed(1);
+
+        process.stdout.write(
+          `\r📥 ${modelName}: [${bar}] ${progress}% (${downloadedMB}MB/${totalMB}MB)`
+        );
+      } else if (chunk.status === "success") {
+        console.log(`\n✅ Modelo ${modelName} baixado com sucesso!`);
+        if (description) {
+          console.log(`🎯 ${description.replace("será usado", "agora funciona")}`);
+        }
+        break;
+      }
+    }
+  } else {
+    console.log(`✅ Modelo ${modelName} já está disponível`);
+  }
+}