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/repositories/conversation.ts

@@ -0,0 +1,78 @@
+import Database from "better-sqlite3";
+
+export interface Conversation {
+  id: string;
+  title: string | null;
+  model: string;
+  created_at: number;
+  updated_at: number;
+}
+
+export class ConversationRepository {
+  constructor(private db: Database.Database) {}
+
+  create(model: string, title?: string): string {
+    const id = crypto.randomUUID();
+    const now = Date.now();
+
+    this.db
+      .prepare(
+        `
+      INSERT INTO conversations (id, title, model, created_at, updated_at)
+      VALUES (?, ?, ?, ?, ?)
+    `
+      )
+      .run(id, title || "Nova conversa", model, now, now);
+
+    return id;
+  }
+
+  findAll(): Conversation[] {
+    return this.db
+      .prepare(
+        `
+      SELECT * FROM conversations 
+      ORDER BY updated_at DESC
+    `
+      )
+      .all() as Conversation[];
+  }
+
+  findById(id: string): Conversation | null {
+    return this.db
+      .prepare(
+        `
+      SELECT * FROM conversations WHERE id = ?
+    `
+      )
+      .get(id) as Conversation | null;
+  }
+
+  updateTitle(id: string, title: string): void {
+    this.db
+      .prepare(
+        `
+      UPDATE conversations 
+      SET title = ?, updated_at = ?
+      WHERE id = ?
+    `
+      )
+      .run(title, Date.now(), id);
+  }
+
+  updateTimestamp(id: string): void {
+    this.db
+      .prepare(
+        `
+      UPDATE conversations 
+      SET updated_at = ?
+      WHERE id = ?
+    `
+      )
+      .run(Date.now(), id);
+  }
+
+  delete(id: string): void {
+    this.db.prepare("DELETE FROM conversations WHERE id = ?").run(id);
+  }
+}