Preserve loader behavior while reducing hidden work (#1996)

* fix(app): preserve loader behavior in retained panels

Keep the running footer mounted across panel switches. Inactive loaders stop their animation work, then realign to the original wall-clock phase before they become visible.

* perf(app): remove inactive loader wrapper worklet

* perf(app): pause hidden turn elapsed timers

* perf(app): reduce loader animation work

Keep one wall-clock-aligned clock for visible loaders and detach retained
hidden loaders without unmounting them. Preserve the 950 ms sequence and
reduced-motion behavior.

packages/app/src/components/synced-loader-state.ts

@@ -0,0 +1,22 @@
+const SYNCED_LOADER_DURATION_MS = 950;
+export const SYNCED_LOADER_DOT_COUNT = 6;
+
+const SYNCED_LOADER_OPACITY_STATES = [
+  [1, 0, 0.78, 0, 0.56, 0.34],
+  [0.78, 1, 0.56, 0, 0.34, 0],
+  [0.56, 0.78, 0.34, 1, 0, 0],
+  [0.34, 0.56, 0, 0.78, 0, 1],
+  [0, 0.34, 0, 0.56, 1, 0.78],
+  [0, 0, 1, 0.34, 0.78, 0.56],
+] as const;
+
+export function getSyncedLoaderStep(nowMs: number): number {
+  "worklet";
+  const elapsedMs = nowMs % SYNCED_LOADER_DURATION_MS;
+  return Math.floor((elapsedMs * SYNCED_LOADER_DOT_COUNT) / SYNCED_LOADER_DURATION_MS);
+}
+
+export function getSyncedLoaderDotOpacity(step: number, dot: number): number {
+  "worklet";
+  return SYNCED_LOADER_OPACITY_STATES[step]?.[dot] ?? 0;
+}