Public reset() supersedes in-flight runs (gen token), cancels
strategy timers, rejects coalesced callers, clears .once cache.
Optional `autoReset: duration` on createTask / createVoidTask
auto-returns state to TaskIdle after TaskDone / TaskFailed.
Refactor: _supersedeInFlight extracted from dispose/reset, doc on
_generation as cross-strategy supersession token. Docs add Picking
TError guidance (Exception / domain / Never / Object) in README +
website + createTask docstring. Example counter gains a
flakyFetch + SnackBar demo. 19 new tests in task_reset_test.dart.