Root cause: capping max_num_tokens to 512 made buffers too small for the
actual 8192-token warmup. slot_hidden had 49152 rows but padded_hidden
only had 6144.
Fix: Revert the 512 cap. Use SHARED padded buffers (not per-layer) to
avoid OOM. Only 72 MB total (not 4.3 GB) since layers run sequentially
and reuse the same buffer. Cudagraph-safe since capture and replay both
run layers sequentially on the same tensor.
biondizzle
b1ac74bb4d