feat(codec): PR-X12 A2 mode bit-pack + A3-intra prediction kernel #444

Job	Run time
clippy/1.95.0	40s
tier4-avx512-check	28s
nostd/thumbv6m-none-eabi/stable	25s
native-backend/stable	8m 25s
Pass MSRV values to other jobs	2s
hpc-stream-parallel/rayon	1m 20s
format/stable	21s
docs/nightly	0s
cargo-careful	0s
cross_test/${{ matrix.target }}/${{ matrix.rust }}	0s
miri	0s
nightly-simd-polyfill	0s
blas-msrv	58s
tests/beta	11m 45s
tests/stable	11m 9s
tests/1.95.0	11m 12s
conclusion	0s
	46m 45s

Provide feedback