Function ssd_scan_fits 

pub fn ssd_scan_fits(state_size: u32) -> bool

Whether the SSD chunked scan physically fits for this state_size.

Callers MUST check this before selecting the SSD path: exceeding the limit makes cuFuncSetAttribute(MAX_DYNAMIC_SHARED) fail with CUDA_ERROR_INVALID_VALUE, which aborts the layer instead of degrading. Measured: Puzzle-75B state_size=96 -> 91392 (fits); Nemotron Nano-30B state_size=128 -> 115968 (does NOT fit, and made the model unservable).