feat: define clean architecture layers and ports

src/application/ports/clock-port.js

@@ -0,0 +1,28 @@
+/**
+ * @typedef {{
+ *   now(): number,
+ *   sleep(milliseconds: number, signal?: AbortSignal): Promise<void>
+ * }} ClockPort
+ */
+
+export const systemClock = Object.freeze({
+  now: () => Date.now(),
+  sleep(milliseconds, signal) {
+    return new Promise((resolve, reject) => {
+      if (signal?.aborted) {
+        reject(signal.reason);
+        return;
+      }
+
+      const timer = setTimeout(resolve, milliseconds);
+      signal?.addEventListener(
+        "abort",
+        () => {
+          clearTimeout(timer);
+          reject(signal.reason);
+        },
+        { once: true },
+      );
+    });
+  },
+});