fix(scheduler): harden scheduled actions and speed limits

- Persist scheduler dispatch markers and retry unacknowledged events across renderer and process restarts.
- Fence queue admission, Torrent moves, and permit activation during system actions with an explicit force path.
- Preserve Aria2 zero-limit overrides and normalize global limits across startup, queued, retry, and live paths.
- Guard scheduler lifecycle races, completion post-actions, settings bindings, and regression coverage.

src/utils/schedulerControl.test.ts

@@ -0,0 +1,13 @@
+import { describe, expect, it } from 'vitest';
+import { beginSchedulerControl, isSchedulerControlCurrent } from './schedulerControl';
+
+describe('scheduler control generation', () => {
+  it('invalidates an older asynchronous scheduler operation', () => {
+    const first = beginSchedulerControl();
+    expect(isSchedulerControlCurrent(first)).toBe(true);
+
+    const second = beginSchedulerControl();
+    expect(isSchedulerControlCurrent(first)).toBe(false);
+    expect(isSchedulerControlCurrent(second)).toBe(true);
+  });
+});