fix: harden account rotation and active download recovery

Apply account enablement changes optimistically and persist rapid toggles sequentially without losing clicks.

Refresh Mega-Debrid API and Web account pools during active downloads, isolate per-account cancellation budgets, rotate within the same conversion attempt, and keep pause, stop, resume, reset, and no-account gates consistent.

Use the native Electron clipboard under Remote Desktop and make support bundle export bounded, redacted, responsive, guarded, visible, and atomic.

Add end-to-end regressions for live account switching, persisted partial recovery, support export, native copy, availability preservation, and the 500 ms telemetry cadence.

tests/account-toggle-queue.test.ts

@@ -0,0 +1,63 @@
+import { describe, expect, it } from "vitest";
+import {
+  SerialTaskQueue,
+  setAccountTargetEnabled,
+  type AccountToggleTarget
+} from "../src/renderer/account-toggle-queue";
+
+describe("account toggle queue", () => {
+  it("keeps every rapid mutation and persists them in click order", async () => {
+    const queue = new SerialTaskQueue();
+    const calls: number[] = [];
+    const first = queue.enqueue(async () => {
+      await new Promise((resolve) => setTimeout(resolve, 15));
+      calls.push(1);
+    });
+    const second = queue.enqueue(async () => {
+      calls.push(2);
+    });
+    const third = queue.enqueue(async () => {
+      calls.push(3);
+    });
+
+    await Promise.all([first, second, third]);
+
+    expect(calls).toEqual([1, 2, 3]);
+  });
+
+  it("continues after a failed mutation", async () => {
+    const queue = new SerialTaskQueue();
+    const calls: number[] = [];
+    const failed = queue.enqueue(async () => {
+      calls.push(1);
+      throw new Error("failed");
+    });
+    const recovered = queue.enqueue(async () => {
+      calls.push(2);
+    });
+
+    await expect(failed).rejects.toThrow("failed");
+    await recovered;
+
+    expect(calls).toEqual([1, 2]);
+  });
+
+  it("combines rapid Mega-Debrid Web activations without losing earlier clicks", () => {
+    const accountIds = ["web-1", "web-2", "web-3"];
+    let settings = {
+      disabledProviders: [],
+      debridLinkDisabledKeyIds: [],
+      megaDebridApiDisabledAccountIds: [],
+      megaDebridWebDisabledAccountIds: [...accountIds],
+      megaDebridDisabledAccountIds: [...accountIds]
+    };
+
+    for (const accountId of accountIds) {
+      const target: AccountToggleTarget = { kind: "mega-web", accountId };
+      settings = setAccountTargetEnabled(settings, target, true);
+    }
+
+    expect(settings.megaDebridWebDisabledAccountIds).toEqual([]);
+    expect(settings.megaDebridDisabledAccountIds).toEqual([]);
+  });
+});