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/vector-search.ts

@@ -0,0 +1,32 @@
+import { generateEmbedding } from "./embeddings";
+import { getDatabase } from "@/database/client";
+import { EmbeddingRepository } from "@/database/repositories/embedding";
+
+export async function semanticSearch(query: string, limit: number = 5) {
+  try {
+    const queryVector = await generateEmbedding(query);
+    const db = getDatabase();
+    const embeddingRepo = new EmbeddingRepository(db);
+
+    return await embeddingRepo.searchSimilar(queryVector, limit);
+  } catch (error) {
+    console.error("Erro na busca semântica:", error);
+    return [];
+  }
+}
+
+export async function addMessageEmbedding(
+  messageId: string,
+  content: string
+): Promise<void> {
+  try {
+    const vector = await generateEmbedding(content);
+    const db = getDatabase();
+    const embeddingRepo = new EmbeddingRepository(db);
+
+    await embeddingRepo.create(messageId, vector);
+  } catch (error) {
+    console.error("Erro ao adicionar embedding:", error);
+    // Não falhar silenciosamente - embedding é opcional
+  }
+}