Add ECDSA signature verification and enhance ComboHandler functionality

- Integrated ECDSA for signature verification in ComboHandler.
- Updated event emissions to include additional parameters for better tracking.
- Improved gas tracking during execution of combo plans.
- Enhanced database interactions for storing and retrieving plans, including conflict resolution and status updates.
- Added new dependencies for security and database management in orchestrator.

orchestrator/src/services/deadLetterQueue.ts

@@ -0,0 +1,62 @@
+import { query } from "../db/postgres";
+
+interface DeadLetterMessage {
+  messageId: string;
+  originalQueue: string;
+  payload: any;
+  error: string;
+  retryCount: number;
+  createdAt: string;
+}
+
+/**
+ * Add message to dead letter queue
+ */
+export async function addToDLQ(
+  queue: string,
+  payload: any,
+  error: string
+): Promise<void> {
+  const messageId = `dlq-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
+
+  await query(
+    `INSERT INTO dead_letter_queue (message_id, queue, payload, error, retry_count, created_at)
+     VALUES ($1, $2, $3, $4, $5, $6)`,
+    [messageId, queue, JSON.stringify(payload), error, 0, new Date().toISOString()]
+  );
+}
+
+/**
+ * Get messages from DLQ for retry
+ */
+export async function getDLQMessages(queue: string, limit = 10): Promise<DeadLetterMessage[]> {
+  const result = await query<DeadLetterMessage>(
+    `SELECT * FROM dead_letter_queue 
+     WHERE queue = $1 AND retry_count < 3
+     ORDER BY created_at ASC
+     LIMIT $2`,
+    [queue, limit]
+  );
+
+  return result.map((row) => ({
+    messageId: row.message_id,
+    originalQueue: row.queue,
+    payload: typeof row.payload === "string" ? JSON.parse(row.payload) : row.payload,
+    error: row.error,
+    retryCount: row.retry_count,
+    createdAt: row.created_at,
+  }));
+}
+
+/**
+ * Increment retry count
+ */
+export async function incrementRetryCount(messageId: string): Promise<void> {
+  await query(
+    `UPDATE dead_letter_queue 
+     SET retry_count = retry_count + 1, updated_at = CURRENT_TIMESTAMP
+     WHERE message_id = $1`,
+    [messageId]
+  );
+}
+