Adds messages/nl.json (AI-initial, informal je/jij register, full key
parity with en.json) and registers nl everywhere the locale list lives:
config, loaders, Intl/date-fns mapping, zod enums, OpenAPI spec, scripts,
the managed-profile picker and the notification locale guards.
Dutch follows the Korean pattern for the AI surfaces (English body plus a
Dutch reply-language footer, no safety-contract matrix) and gets its own
banks in the outbound safety screen (dose, risk, causal, continuation),
the prose-grounding and citation-coverage tables, the reference-range
prose and the no-key fallback copy, each with Dutch test fixtures.
PHQ-9 / GAD-7 / WHO-5 are not marked validated for nl yet: the Dutch
wording has not been read against the published forms, so Dutch readers
get the English items plus the existing note until it has.
Marc-André Bombeck