Fix Mega-Web rotation skipping accounts on a timeout abort

When a Mega-Web account's unrestrict aborts because the shared unrestrict
timeout fired while it was running, give that account a 2-min cooldown
(only if it actually ran >=8s, so a quick user-cancel does not cool it
down). The download-manager retry then skips the cooled-down account and
rotates to the next one, instead of hammering the same account every 60s.

- debrid.ts: handle the abort in the rotation catch before classifyAccountFailure
- rotation log event TIMEOUT_COOLDOWN (+ renderer label) replaces the misleading
  red "fataler Fehler" for this case
- RD_MEGA_ABORT_MIN_RUN_MS env override for the run-length threshold
- 2 regression tests (cooldown set -> next call rotates; quick abort -> no cooldown)

src/renderer/App.tsx

@@ -1150,6 +1150,10 @@ function rotationEventText(ev: { event: string; cooldownSec?: number; next?: str
       return `fehlgeschlagen${cd}${nx}`;
     }
     case "FATAL": return "abgebrochen (fataler Fehler)";
+    case "TIMEOUT_COOLDOWN": {
+      const cd = ev.cooldownSec ? `, Cooldown ${ev.cooldownSec}s` : "";
+      return `Timeout/Abbruch${cd} → nächster Account beim Retry`;
+    }
     case "SKIP_COOLDOWN": return untilRestart ? "übersprungen (bis Neustart gesperrt)" : "übersprungen (Cooldown aktiv)";
     case "SKIP_DISABLED": return "übersprungen (deaktiviert)";
     case "SKIP_DAILY_LIMIT": return "übersprungen (Tageslimit erreicht)";