Previously the global GPU-toggle total was set once and never
overridden, so a first scan on the local 1-GPU container left
the Run-panel GPU button row stuck on GPU 0 even after switching
to a 4-GPU remote host. Now any scan returning a positive total
updates the binding; zero/missing values still don't clobber a
known-good count (no flicker during in-flight re-probes).
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