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.

database/migrations.ts

@@ -0,0 +1,69 @@
+import Database from "better-sqlite3";
+import fs from "fs";
+import path from "path";
+
+export function runMigrations(db: Database.Database): void {
+  // Criar tabela de migrações
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS _migrations (
+      id INTEGER PRIMARY KEY,
+      name TEXT NOT NULL UNIQUE,
+      applied_at INTEGER NOT NULL
+    );
+  `);
+
+  // Verificar migrações aplicadas
+  const applied = db.prepare("SELECT name FROM _migrations").all() as Array<{
+    name: string;
+  }>;
+  const appliedNames = new Set(applied.map((m) => m.name));
+
+  // Aplicar migração inicial se não foi aplicada
+  if (!appliedNames.has("001_initial_schema")) {
+    console.log("📋 Aplicando migração: 001_initial_schema");
+
+    const schemaPath = path.join(process.cwd(), "database", "schema.sql");
+    const schema = fs.readFileSync(schemaPath, "utf-8");
+
+    db.exec(schema);
+
+    // Registrar migração
+    db.prepare("INSERT INTO _migrations (name, applied_at) VALUES (?, ?)").run(
+      "001_initial_schema",
+      Date.now()
+    );
+
+    console.log("✅ Migração 001_initial_schema aplicada");
+  }
+
+  // Inicializar extensão vetorial se disponível
+  try {
+    const extPath = path.join(
+      process.cwd(),
+      "database",
+      "extensions",
+      "vector.so"
+    );
+    if (fs.existsSync(extPath)) {
+      db.loadExtension(extPath);
+
+      // Inicializar índice vetorial
+      db.exec(`
+        SELECT vector_init('embeddings', 'vector', 'type=FLOAT32,dimension=384');
+      `);
+
+      // Quantizar para busca mais rápida
+      db.exec(`
+        SELECT vector_quantize('embeddings', 'vector');
+      `);
+
+      console.log("🔍 Extensão vetorial carregada e inicializada");
+    } else {
+      console.log(
+        "⚠️  Extensão vetorial não encontrada - busca vetorial desabilitada"
+      );
+    }
+  } catch (error) {
+    console.log("⚠️  Erro ao carregar extensão vetorial:", error);
+  }
+}