fix(fish-speech): use CUDA toolkit ptxas

Prefer an explicitly configured Triton assembler, otherwise use the executable ptxas from CUDA_HOME so torch.compile can target GPU architectures newer than Triton bundled tooling.

Assisted-by: Codex:gpt-5
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

scripts/build/fish-speech-ptxas_test.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+set -euo pipefail
+
+WORK=$(mktemp -d)
+trap 'rm -rf "$WORK"' EXIT
+
+REPO_ROOT=$(dirname "$(dirname "$(dirname "$(realpath "$0")")")")
+BACKEND_DIR="$WORK/fish-speech"
+mkdir -p "$BACKEND_DIR/common" "$WORK/cuda/bin"
+cp "$REPO_ROOT/backend/python/fish-speech/run.sh" "$BACKEND_DIR/run.sh"
+
+cat > "$BACKEND_DIR/common/libbackend.sh" <<'LIBBACKEND'
+startBackend() {
+    printf '%s\n' "${TRITON_PTXAS_PATH:-}"
+}
+LIBBACKEND
+
+fail() {
+    echo "FAIL: $*"
+    exit 1
+}
+
+touch "$WORK/cuda/bin/ptxas"
+chmod +x "$WORK/cuda/bin/ptxas"
+
+got=$(CUDA_HOME="$WORK/cuda" bash "$BACKEND_DIR/run.sh")
+[ "$got" = "$WORK/cuda/bin/ptxas" ] || \
+    fail "expected toolkit ptxas, got '$got'"
+
+got=$(CUDA_HOME="$WORK/cuda" TRITON_PTXAS_PATH=/custom/ptxas \
+    bash "$BACKEND_DIR/run.sh")
+[ "$got" = "/custom/ptxas" ] || \
+    fail "explicit TRITON_PTXAS_PATH was overwritten with '$got'"
+
+chmod -x "$WORK/cuda/bin/ptxas"
+got=$(CUDA_HOME="$WORK/cuda" bash "$BACKEND_DIR/run.sh")
+[ -z "$got" ] || fail "non-executable ptxas was selected as '$got'"
+
+echo "PASS: fish-speech selects a usable toolkit ptxas"