layernorm: FP32 SimplifiedLayerNorm/SkipSLN to prevent MoE routing collapse - #5259

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@1bd1e32a3bdc45362d1e726936510720a7c30a57, actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683, actions/setup-python@7f4fc3e22c37d6ff65e88745f38bd3157c663f7c, jwlawson/actions-setup-cmake@710e05536f2b819d5918f51a5de5b392e99bba3c, KyleMayes/install-llvm-action@ebc0426251bc40c7cd31162802432c68818ab8f0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/