hero_logo_visible is nullable — null means "inherit the global
branding_logo_display_hero toggle" (#756, migration 152). But the create and
update validators used `.optional()` without `{ nullable: true }`, which only
skips `undefined`; an explicit `null` still ran `.isBoolean()` and failed with
HTTP 400 "Invalid value". Saving an event with `hero_logo_visible: null` (the
inherit state the frontend sends) was rejected on v3.45.2.
- Both routes: `body('hero_logo_visible').optional({ nullable: true }).isBoolean()`,
matching the already-correct `hero_logo_size` rule next to it.
- Create handler: guard on `!= null` instead of `!== undefined` so an explicit
null stores NULL (inherit) rather than being coerced to 0/false by
formatBoolean on SQLite. The update handler already did `=== null ? null`.
Left hero_logo_position on plain `.optional()` on purpose: its column is NOT
NULL (no inherit migration) and its handler always resolves to a concrete value
via `|| brandingDefaults`, so null is genuinely invalid there — allowing it
would trade the 400 for a 500.
Adds smoke tests: PUT accepts hero_logo_visible: null and stores NULL; a
non-boolean value is still rejected.
Paul Nothaft
b97b130cad