Add 3DGS certified field kernel substrate plan #481

Job	Run time
format/stable	21s
native-backend/stable	7m 49s
hpc-stream-parallel/rayon	1m 19s
tier4-avx512-check	31s
Pass MSRV values to other jobs	2s
cargo-careful	40s
docs/nightly	51s
clippy/1.95.0	42s
nostd/thumbv6m-none-eabi/stable	29s
miri	1m 9s
nightly-simd-polyfill	41s
cross_test/${{ matrix.target }}/${{ matrix.rust }}	-1s
blas-msrv	49s
tests/stable	10m 43s
tests/1.95.0	10m 45s
tests/beta	11m 18s
conclusion	0s
	48m 8s

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