fix: quote $MOE_LAYER_FREQ

[lawrence-harmonic]

If there is a file named "1", then --moe-layer-freq will be wrong.

Explanation:

$ echo [1,1,1]
[1,1,1]
$ touch 1
$ echo [1,1,1]
1
$ echo "[1,1,1]"
[1,1,1]

In SLIME context:

$ source scripts/models/qwen3.5-35B-A3B.sh
$ echo ${MODEL_ARGS[@]}
--spec slime_plugins.models.qwen3_5 get_qwen3_5_spec --disable-bias-linear --qk-layernorm --group-query-attention --num-attention-heads 16 --num-query-groups 2 --kv-channels 256 --num-layers 40 --hidden-size 2048 --ffn-hidden-size 512 --use-gated-attention --normalization RMSNorm --apply-layernorm-1p --position-embedding-type rope --norm-epsilon 1e-6 --rotary-percent 0.25 --swiglu --untie-embeddings-and-output-weights --vocab-size 248320 --rotary-base 10000000 --moe-ffn-hidden-size 512 --moe-shared-expert-intermediate-size 512 --moe-router-score-function softmax --moe-token-dispatcher-type alltoall --moe-router-topk 8 --moe-layer-freq [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1] --num-experts 256 --moe-grouped-gemm --moe-token-drop-policy probs --moe-router-dtype fp32 --moe-permute-fusion --moe-aux-loss-coeff 0 --attention-output-gate --moe-shared-expert-gate
$ touch 1
$ source scripts/models/qwen3.5-35B-A3B.sh
$ echo ${MODEL_ARGS[@]}
--spec slime_plugins.models.qwen3_5 get_qwen3_5_spec --disable-bias-linear --qk-layernorm --group-query-attention --num-attention-heads 16 --num-query-groups 2 --kv-channels 256 --num-layers 40 --hidden-size 2048 --ffn-hidden-size 512 --use-gated-attention --normalization RMSNorm --apply-layernorm-1p --position-embedding-type rope --norm-epsilon 1e-6 --rotary-percent 0.25 --swiglu --untie-embeddings-and-output-weights --vocab-size 248320 --rotary-base 10000000 --moe-ffn-hidden-size 512 --moe-shared-expert-intermediate-size 512 --moe-router-score-function softmax --moe-token-dispatcher-type alltoall --moe-router-topk 8 --moe-layer-freq 1 --num-experts 256 --moe-grouped-gemm --moe-token-drop-policy probs --moe-router-dtype fp32 --moe-permute-fusion --moe-aux-loss-coeff 0 --attention-output-gate --moe-shared-expert-gate