fix&feature: fixxing some logical bogs and adding cursor pagination

src/modules/utils/providers/cursor-pagination.utils.ts

@@ -0,0 +1,28 @@
+import { BadRequestException } from "@nestjs/common";
+
+interface CursorPayload {
+  priority: number;
+  createdAt: Date;
+  id: string;
+}
+
+export function decodeCursor(cursor: string): CursorPayload {
+  try {
+    const decoded = Buffer.from(cursor, "base64").toString("utf-8");
+    const [priorityStr, timestamp, id] = decoded.split("|");
+    if (!priorityStr || !timestamp || !id) throw new Error("Invalid format");
+    const priority = parseInt(priorityStr, 10);
+    if (isNaN(priority)) throw new Error("Priority not a number");
+    const createdAt = new Date(timestamp);
+    if (isNaN(createdAt.getTime())) throw new Error("Invalid date");
+    return { priority, createdAt, id };
+  } catch {
+    throw new BadRequestException(
+      "Invalid cursor. Expected base64‑encoded string containing priority, ISO date and id (separated by '|').",
+    );
+  }
+}
+
+export function encodeCursor(task: { priority: number; createdAt: Date; id: string }): string {
+  return Buffer.from(`${task.priority}|${task.createdAt.toISOString()}|${task.id}`).toString("base64");
+}