POST /remove-background gains an optional cross_check form field
(1/0/true/false/yes/no/on/off; empty = service default). The effective
state is reported in the X-BGFilter-Cross-Check response header.
The cross-check model is now never preloaded at startup: the first
request that enables it pays the one-time load (measured ~8 s on top of
the ~50 s cc inference), after which the instance is cached and shared.
Verified with a functional test against PipelineManager: cc-off requests
never load the model, cc=1 lazy-loads then reuses the cached instance,
and omitting the field falls back to the service default.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
lhk229
8417653598