Extends the Fase 10.8 Accept-Language parser to surface `'eu'` as a third
known primary subtag, gated on the same q ≥ 0.5 threshold the existing
`'es'` path uses. `'en'` continues to short-circuit because it's the
source language. `AppLanguage` widens to `'en' | 'es' | 'eu'`.
Tests:
* Unit (apps/web): LANG-U-EU-01 bare 'eu', LANG-U-EU-02 'eu-ES',
LANG-U-EU-03 'eu-FR;q=0.5,en;q=0.4' (borderline q wins), LANG-U-EU-04
navigator.languages array — 4 new specs, all green.
* Integration (packages/test-utils): LANG-INT-EU-01 user updates own
language=eu, LANG-INT-EU-02 user attempts language='fr' and gets the
Postgres 22P02 from the ENUM (cast through `as unknown as` so the
narrow TS type doesn't block the test).
The integration negative case lands on the language_code ENUM gate from
migration 028, not RLS — it would still fail even from a service-role
client.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Oier Bravo Urtasun
e9c29dcf38