The one place each host capability is decided. lx.supports(), the FFI
capability bitmask, and the optional lx.* members all read these, so they
cannot drift apart.
The capabilities: section, shared verbatim between the CLI (parsing
lingxia.yaml, writing app.json) and the runtime (reading app.json) —
one definition so a capability can never exist on one side only.
deny_unknown_fields gives lingxia.yaml typo errors; the runtime always
reads an app.json generated by the same CLI build, so it never sees fields
this struct lacks.
Runtime half of splash:. Images and colors are platform resources; only
the minimum hold time is a runtime decision, and the upper bound is a
framework constant that hosts deliberately cannot configure.
Active environment version baked into the running build. Defaults to
EnvVersion::Release before set_app_config is called and for any
app.json produced before the envVersion field existed.