record performance fixes: FA_ALL_QUANTS build flag (dankserver), RDNA triton FA env (dankclaw)

- frank-default-large: GGML_CUDA_FA_ALL_QUANTS=ON is mandatory in the
  FastMTP build; without it q8_0 KV + FA falls back to a slow path and
  prefill collapses ~12x (95 -> 1312 t/s at 8K, measured)
- frank-default-small: FLASH_ATTENTION_TRITON_AMD_ENABLE=TRUE + pure-python
  flash_attn (triton_amd) + stub; without it the vision encoder warmup
  OOMs via torch SDPA

scripts/frank-default-large.env

@@ -15,6 +15,10 @@ MODEL_DIR=/home/dank/models/hauhaucs-qwen38
 MODEL_FILE=Qwen3.8-27B-Uncensored-HauhauCS-Aggressive-IQ4_XS.gguf
 DRAFT_FILE=Qwen3.8-27B-Uncensored-HauhauCS-Aggressive-FastMTP-32K.gguf
 # Patched llama.cpp binary. The FastMTP sidecar needs the patch; see AGENTS.md.
+# REQUIRED build flags: -DGGML_CUDA_FA=ON -DGGML_CUDA_FA_ALL_QUANTS=ON.
+# Without FA_ALL_QUANTS the q8_0 KV + flash attention fall back to a slow
+# path and prefill collapses ~12x (95 t/s vs 1300+ t/s at 8K prompt,
+# measured 2026-08-17). Do not rebuild without it.
 LLAMA_BIN=/home/dank/llama.cpp-fastmtp/build/bin/llama-server
 
 ALIAS=frank-default-large