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.

app/api/conversations/route.ts

@@ -0,0 +1,54 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getDatabase } from "@/database/client";
+import { ConversationRepository } from "@/database/repositories/conversation";
+import { MessageRepository } from "@/database/repositories/message";
+import { generateChatTitle } from "@/lib/embeddings";
+
+export async function GET() {
+  try {
+    const db = getDatabase();
+    const conversationRepo = new ConversationRepository(db);
+
+    const conversations = conversationRepo.findAll();
+
+    return NextResponse.json(conversations);
+  } catch (error) {
+    console.error("Erro ao buscar conversas:", error);
+    return NextResponse.json(
+      { error: "Erro interno do servidor" },
+      { status: 500 }
+    );
+  }
+}
+
+export async function POST(request: NextRequest) {
+  try {
+    const { model, firstMessage } = await request.json();
+
+    if (!model) {
+      return NextResponse.json(
+        { error: "Modelo é obrigatório" },
+        { status: 400 }
+      );
+    }
+
+    const db = getDatabase();
+    const conversationRepo = new ConversationRepository(db);
+
+    // Gerar título se primeira mensagem fornecida
+    let title = "Nova conversa";
+    if (firstMessage) {
+      title = await generateChatTitle(firstMessage);
+    }
+
+    const conversationId = conversationRepo.create(model, title);
+
+    return NextResponse.json({ id: conversationId, title });
+  } catch (error) {
+    console.error("Erro ao criar conversa:", error);
+    return NextResponse.json(
+      { error: "Erro interno do servidor" },
+      { status: 500 }
+    );
+  }
+}