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.

components/chat/ConversationSidebar.tsx

@@ -0,0 +1,117 @@
+"use client";
+
+import { useState, useEffect } from "react";
+import { MessageSquare, Plus, Trash2 } from "lucide-react";
+
+type Conversation = {
+  id: string;
+  title: string;
+  model: string;
+  updated_at: number;
+};
+
+type ConversationSidebarProps = {
+  currentConversationId: string | null;
+  onSelectConversation: (id: string) => void;
+  onNewConversation: () => void;
+  refreshTrigger?: number; // Para forçar atualização
+};
+
+export function ConversationSidebar({
+  currentConversationId,
+  onSelectConversation,
+  onNewConversation,
+  refreshTrigger,
+}: ConversationSidebarProps) {
+  const [conversations, setConversations] = useState<Conversation[]>([]);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    loadConversations();
+  }, []);
+
+  // Recarregar conversas quando refreshTrigger mudar
+  useEffect(() => {
+    if (refreshTrigger !== undefined) {
+      loadConversations();
+    }
+  }, [refreshTrigger]);
+
+  const loadConversations = async () => {
+    try {
+      const response = await fetch("/api/conversations");
+      const data = await response.json();
+      setConversations(data);
+    } catch (error) {
+      console.error("Erro ao carregar conversas:", error);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  const handleDelete = async (id: string, e: React.MouseEvent) => {
+    e.stopPropagation();
+
+    if (!confirm("Deletar esta conversa?")) return;
+
+    try {
+      await fetch(`/api/conversations/${id}`, { method: "DELETE" });
+      setConversations((prev) => prev.filter((c) => c.id !== id));
+
+      if (currentConversationId === id) {
+        onNewConversation();
+      }
+    } catch (error) {
+      console.error("Erro ao deletar conversa:", error);
+    }
+  };
+
+  return (
+    <div className="w-64 h-full bg-[var(--surface)] border-r border-[var(--border)] flex flex-col">
+      {/* Header */}
+      <div className="p-4 border-b border-[var(--border)]">
+        <button
+          onClick={onNewConversation}
+          className="w-full flex items-center justify-center gap-2 px-4 py-2 bg-[var(--accent)] text-white rounded-lg hover:opacity-90 transition-opacity"
+        >
+          <Plus className="h-4 w-4" />
+          Nova Conversa
+        </button>
+      </div>
+
+      {/* Lista de Conversas */}
+      <div className="flex-1 overflow-y-auto p-2">
+        {loading ? (
+          <div className="text-center p-4 text-sm text-[var(--foreground)]/60">
+            Carregando...
+          </div>
+        ) : conversations.length === 0 ? (
+          <div className="text-center p-4 text-sm text-[var(--foreground)]/60">
+            Nenhuma conversa ainda
+          </div>
+        ) : (
+          conversations.map((conv) => (
+            <div
+              key={conv.id}
+              onClick={() => onSelectConversation(conv.id)}
+              className={`w-full flex items-center gap-2 p-3 rounded-lg mb-1 text-left transition-colors group cursor-pointer ${
+                currentConversationId === conv.id
+                  ? "bg-[var(--accent)]/10 text-[var(--accent)]"
+                  : "hover:bg-[var(--background)]"
+              }`}
+            >
+              <MessageSquare className="h-4 w-4 flex-shrink-0" />
+              <span className="flex-1 text-sm truncate">{conv.title}</span>
+              <button
+                onClick={(e) => handleDelete(conv.id, e)}
+                className="p-1 hover:bg-[var(--background)] rounded opacity-0 group-hover:opacity-100 transition-opacity"
+              >
+                <Trash2 className="h-3 w-3" />
+              </button>
+            </div>
+          ))
+        )}
+      </div>
+    </div>
+  );
+}