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/preferences.ts

@@ -0,0 +1,99 @@
+import Database from "better-sqlite3";
+import path from "path";
+import fs from "fs";
+
+let db: Database.Database | null = null;
+
+export async function getPreferencesDb(): Promise<Database.Database> {
+  if (!db) {
+    try {
+      const dbPath = path.join(
+        process.cwd(),
+        "database",
+        "ollahub-preferences.db"
+      );
+
+      // Garantir que o diretório existe
+      const dbDir = path.dirname(dbPath);
+      if (!fs.existsSync(dbDir)) {
+        fs.mkdirSync(dbDir, { recursive: true });
+      }
+
+      db = new Database(dbPath);
+
+      // Configurações de performance
+      db.pragma("journal_mode = WAL");
+      db.pragma("synchronous = NORMAL");
+      db.pragma("foreign_keys = ON");
+      db.pragma("cache_size = 10000");
+      db.pragma("temp_store = memory");
+
+      // Criar tabela de preferências se não existir
+      db.exec(`
+        CREATE TABLE IF NOT EXISTS user_preferences (
+          user_id TEXT PRIMARY KEY,
+          preferences TEXT NOT NULL,
+          updated_at INTEGER NOT NULL
+        );
+      `);
+
+      console.log("✅ Banco de preferências SQLite conectado com sucesso");
+    } catch (error) {
+      console.warn("⚠️ Erro ao conectar banco de preferências:", error);
+      throw error;
+    }
+  }
+  return db;
+}
+
+export async function getPreferences(userId: string = "default"): Promise<any> {
+  try {
+    const database = await getPreferencesDb();
+    const stmt = database.prepare(
+      "SELECT preferences FROM user_preferences WHERE user_id = ?"
+    );
+    const result = stmt.get(userId) as { preferences: string } | undefined;
+
+    if (result) {
+      return JSON.parse(result.preferences);
+    }
+
+    // Retornar preferências padrão
+    return {
+      selectedModel: null,
+      systemPrompt: "",
+      device: "auto",
+      gpuIndex: 0,
+      numGpu: 1,
+    };
+  } catch (error) {
+    console.error("Erro ao buscar preferências:", error);
+    throw error;
+  }
+}
+
+export async function setPreferences(
+  userId: string = "default",
+  preferences: any
+): Promise<void> {
+  try {
+    const database = await getPreferencesDb();
+    const stmt = database.prepare(`
+      INSERT OR REPLACE INTO user_preferences (user_id, preferences, updated_at)
+      VALUES (?, ?, ?)
+    `);
+
+    stmt.run(userId, JSON.stringify(preferences), Date.now());
+    console.log("✅ Preferências salvas no SQLite");
+  } catch (error) {
+    console.error("Erro ao salvar preferências:", error);
+    throw error;
+  }
+}
+
+export function closePreferencesDb(): void {
+  if (db) {
+    db.close();
+    db = null;
+  }
+}