Add playlist browser overlay modal (#37)

src/core/services/immersion-tracker/time.ts

@@ -1,4 +1,26 @@
+declare global {
+  var __subminerTestNowMs: number | string | undefined;
+}
+
+function getMockNowMs(testNowMs: number | string | undefined): number | null {
+  if (typeof testNowMs === 'number' && Number.isFinite(testNowMs)) {
+    return Math.trunc(testNowMs);
+  }
+  if (typeof testNowMs === 'string') {
+    const parsed = Number(testNowMs.trim());
+    if (Number.isFinite(parsed)) {
+      return Math.trunc(parsed);
+    }
+  }
+  return null;
+}
+
 export function nowMs(): number {
+  const mockedNowMs = getMockNowMs(globalThis.__subminerTestNowMs);
+  if (mockedNowMs !== null) {
+    return mockedNowMs;
+  }
+
   const perf = globalThis.performance;
   if (perf && Number.isFinite(perf.timeOrigin)) {
     return Math.floor(perf.timeOrigin + perf.now());