The admin user edit modal rejected concurrency < 1, so a user whose
concurrency is already 0 could not be saved at all — the guard runs
before the request, blocking notes, password, role and RPM edits on that
user too.
Everywhere else already treats 0 as unlimited: the gateway skips slot
limiting when maxConcurrency <= 0 (ConcurrencyService.AcquireUserSlot),
the batch limits endpoint binds concurrency with min=0, and the bulk edit
modal only rejects negative values.
Reject negative and non-integer values instead, mirror the RPM field with
min/step and a "0 = unlimited" placeholder and hint, and rename the error
key to match its new meaning. Account concurrency is unchanged.
Yoga Sakti
5dfad32b87