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/embedding.ts

@@ -0,0 +1,100 @@
+import Database from "better-sqlite3";
+
+export interface Embedding {
+  id: string;
+  message_id: string;
+  vector: Buffer;
+}
+
+export interface SearchResult {
+  id: string;
+  content: string;
+  role: string;
+  distance: number;
+  conversation_id: string;
+}
+
+export class EmbeddingRepository {
+  constructor(private db: Database.Database) {}
+
+  async create(messageId: string, vector: Float32Array): Promise<void> {
+    const id = crypto.randomUUID();
+    const blob = Buffer.from(vector.buffer);
+
+    this.db
+      .prepare(
+        `
+      INSERT INTO embeddings (id, message_id, vector)
+      VALUES (?, ?, ?)
+    `
+      )
+      .run(id, messageId, blob);
+  }
+
+  async searchSimilar(
+    queryVector: Float32Array,
+    limit: number = 5
+  ): Promise<SearchResult[]> {
+    const queryBlob = Buffer.from(queryVector.buffer);
+
+    try {
+      // Tentar busca vetorial se extensão estiver disponível
+      return this.db
+        .prepare(
+          `
+        SELECT 
+          m.id, m.content, m.role, m.conversation_id,
+          vector_distance(e.vector, ?) as distance
+        FROM embeddings e
+        JOIN messages m ON m.id = e.message_id
+        ORDER BY distance ASC
+        LIMIT ?
+      `
+        )
+        .all(queryBlob, limit) as SearchResult[];
+    } catch (error) {
+      console.warn(
+        "Busca vetorial não disponível, usando busca simples:",
+        error
+      );
+
+      // Fallback: busca simples por conteúdo
+      return this.db
+        .prepare(
+          `
+        SELECT 
+          m.id, m.content, m.role, m.conversation_id,
+          0.0 as distance
+        FROM messages m
+        WHERE m.content LIKE ?
+        ORDER BY m.timestamp DESC
+        LIMIT ?
+      `
+        )
+        .all(`%${queryVector.toString()}%`, limit) as SearchResult[];
+    }
+  }
+
+  findByMessage(messageId: string): Embedding | null {
+    return this.db
+      .prepare(
+        `
+      SELECT * FROM embeddings WHERE message_id = ?
+    `
+      )
+      .get(messageId) as Embedding | null;
+  }
+
+  deleteByMessage(messageId: string): void {
+    this.db
+      .prepare("DELETE FROM embeddings WHERE message_id = ?")
+      .run(messageId);
+  }
+
+  count(): number {
+    const result = this.db
+      .prepare("SELECT COUNT(*) as count FROM embeddings")
+      .get() as { count: number };
+    return result.count;
+  }
+}