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)