createFromFormat() only returns false on hard parse failures.
Impossible dates such as 2026-02-31 were silently normalized
into March, so a confirmed event could land on a different day
than the booking link supplied. Non-padded values like
2026-2-3T10:00 were also accepted and reformatted.
Parse with a leading "!" so no current-date fields leak in,
require zero warnings and errors from getLastErrors(), and
round-trip the value through the format. Impossible dates,
out-of-range components and non-padded values now throw in
both the confirmation and the creation stage.
stefan.tollkuehn
2b3e96e50a