Point the llama assert at the right root, and name the Intel limitation

The tauri leg installs to the legacy root because --tauri refuses a custom
UNSLOTH_STUDIO_HOME. Its install succeeds end to end, but llama.cpp lives at
<root>/llama.cpp while the venv is at <root>/studio, so the assert was pointed one
level too deep.

On macos-15-intel /usr/bin/git keeps working once the CLT are gone, so it is not
CLT-provided there and no masking can remove it, while cc and clang do become
stubs. Calling that 'masking failed' was wrong. That leg allowlists git
explicitly and says why, so the assert stays strict everywhere else.

.github/scripts/clean-machine-assert.sh

@@ -38,6 +38,16 @@ for check in "$@"; do
       for tool in git cc clang cmake; do
         command -v "$tool" >/dev/null 2>&1 || { ok "$tool not on PATH"; continue; }
         if "$tool" --version >/dev/null 2>&1; then
+          # On Intel runners /usr/bin/git keeps working once the CLT are gone, so it
+          # is not CLT-provided there and no masking can remove it. cc and clang do
+          # become stubs, and the consumer path needs no git on macOS, so report it
+          # rather than calling the simulation broken.
+          case " ${UNSLOTH_CLEAN_ALLOW_WORKING:-} " in
+            *" $tool "*)
+              echo "[assert] NOTE $tool still works ($(command -v "$tool")); allowed on this runner"
+              continue
+              ;;
+          esac
           fail "toolchain still usable: '$tool --version' succeeded ($(command -v "$tool")); masking failed"
         else
           ok "$tool present but non-functional (CLT stub), as on a clean Mac"