frank-default-small: ncmoe 35->36 for prefill stability

Fix a live crash: cuBLAS cudaErrorInvalidValue in ggml_cuda_mul_mat_cublas
killed the service during a 145k-token prefill burst at ncmoe35/ub3072.

ncmoe 36 moves one more expert layer to CPU: frees ~0.75 GiB peak VRAM
(grid: peak 8606 vs 9360 MiB at ub3072) for -2% prefill / -2% decode.
Keeps prefill priority (top ubatch tier). Docs synced; noted fallback
GGML_CUDA_FORCE_MMQ=1 if pressure persists.

docs/frank-default-small-benchmark.md

@@ -101,24 +101,31 @@ and fails, which matches the recorded OOMs at `ncmoe 32` and `33`.
 
 ## Chosen State
 
-Prefill speed is the priority for this workload, so the final state takes
-the top prefill tier while keeping a safe headroom margin:
+Prefill speed is the priority, so the state keeps the top prefill tier and
+moves one expert layer to CPU for stability:
 
 ```
---n-cpu-moe 35     # 5 expert layers on GPU
+--n-cpu-moe 36     # 4 expert layers on GPU
 --batch-size   8192
 --ubatch-size  3072
 ```
 
-This gives prefill about 1458 t/s at 16384 prompt tokens, generation about
-45.4 t/s, and about 1.2 GiB of headroom at the 800000-token pool. Both are
-chosen because generation does not depend on `ubatch`: `ubatch 3072` reaches
-the best prefill speed with no cost to decode.
+This gives prefill about 1427 t/s at 16384 prompt tokens, generation about
+44.4 t/s, and about 3.0 GiB of headroom at the 800000-token pool.
+
+`ncmoe 36` came from a live crash rather than this sweep. At `ncmoe 35` with
+`ubatch 3072`, a big prefill burst failed a cuBLAS call under memory
+pressure (a `cudaErrorInvalidValue` in `ggml_cuda_mul_mat_cublas`), which
+killed the service. Raising `ncmoe` one step frees about 0.75 GiB of peak
+VRAM (the grid shows `ncmoe 36 - ubatch 3072` peak 8606 MiB versus 9360 MiB
+at `ncmoe 35`) for about 2 percent less prefill and 2 percent less decode.
+
+If a crash still occurs under load, set `GGML_CUDA_FORCE_MMQ=1` to bypass
+the cuBLAS path for quantized matmuls, or drop `ubatch`, or shrink the
+context pool.
 
 If decode speed matters more than prefill, swap to `ncmoe 32 - ubatch 1024`
 (generation about 48.7 t/s, prefill about 766 t/s, about 1.0 GiB headroom).
-If stability headroom matters most, use `ncmoe 34 - ubatch 1536` (about 2.0
-GiB headroom).
 
 ## Limitations