Self-registration stored values verbatim, so trailing whitespace could
produce rows that lookup code (which trims input) silently misses.
Trim username and email before validation and INSERT in registerUser,
adminService.updateUser, and oidcService.findOrCreateUser. updateSettings
and adminService.createUser already trimmed correctly.
Adds a one-shot backfill migration (trimUserWhitespace) that trims
existing dirty rows; collisions are resolved by appending __migrated_<id>
to the value with a loud console.warn so operators can review affected
accounts.
18 new tests covering registration trim, duplicate detection, admin
update trim, trip-member lookup regression, and all migration branches.
jubnl