Update a fusion baseline

tests/fusion/<BACKEND>.csv is the test-fusion golden baseline: arch,moe,mode,label,count, where count is how many times a fusion label matched per graph run. See tests/fusion/README.md.

Re-record only when the counts moved for the reason the contributor intended. A row failing on nmse_fus (> 1e-4) is a fused-vs-unfused correctness bug, not baseline drift - fix it, never record it away.

Steps

cmake -B build -DCMAKE_BUILD_TYPE=Release -DGGML_METAL=ON       # enable the target backend
cmake --build build --config Release --target test-llama-archs --target test-fusion -j

rm -rf build-ci-models && mkdir -p build-ci-models              # always regenerate
./build/bin/test-llama-archs -o build-ci-models

D=MTL0; B=tests/fusion/MTL.csv; T=/tmp/$(basename $B)   # keep the target backend/device in sync
./build/bin/test-fusion --models build-ci-models --device $D --check $B   # read the FAIL rows
./build/bin/test-fusion --models build-ci-models --device $D --record $T
diff $B $T
cp $T $B
./build/bin/test-fusion --models build-ci-models --device $D --check $B   # 0 failed, exit 0

• Read the diff before applying it. Every added, removed or changed row must be explainable by the change under review; an unexplained row means the run picked up something unintended.
• expected 0 in a FAIL row = no baseline row for that label (new arch, or a fusion newly firing); non-zero expected = count changed; fusion ... is no longer matched = row stopped firing.
• --record rewrites the whole file, so never record a partial run (--model FILE, a filtered models dir) - it drops the rows of every architecture that was not run.
• --record marks every row ok; only the --check run validates.