Regex compiled per-call in hot paths

[windoze95]

Location: internal/service/import.go:382,550 and internal/service/user.go:265-278

regexp.MustCompile is called inside function bodies (extractJSONLD, parseISO8601Duration) meaning the regex is recompiled on every call. ValidatePassword calls regexp.MatchString 4 times per validation, each compiling the regex.

Fix: move all regex compilation to package-level var statements.