_homebox_offer_authelia_oidc() automates Homebox's own native OIDC support
(real env vars, not paste-in instructions) — confirmed the exact variable
names and redirect path against homebox.software's own OIDC docs and
authelia.com's Homebox integration page, not guessed. Needs PKCE, unlike
Mealie/ActualBudget.
The stock compose template listed env vars individually in `environment:`
rather than using `env_file: .env` — added to the template, and patched
onto any pre-existing install's compose file the first time this offer
runs, or the OIDC vars written to .env would never actually reach the
container.
_homebox_offer_disable_local_login() is the separate, gated "replace
local login entirely" step (HBOX_OPTIONS_ALLOW_LOCAL_LOGIN=false +
HBOX_OIDC_AUTO_REDIRECT=true), same "have you tested it first" pattern as
Mealie/Beszel.