Add backlog tasks and launcher time helper tests

- Track follow-up cleanup work in Backlog.md
- Replace Date.now usage with shared nowMs helper
- Add launcher args/parser and core regression tests

launcher/time.ts

@@ -0,0 +1,8 @@
+export function nowMs(): number {
+  const perf = globalThis.performance;
+  if (perf) {
+    return Math.floor(perf.timeOrigin + perf.now());
+  }
+
+  return Number(process.hrtime.bigint() / 1000000n);
+}