try aarch64 simd jetscii with const new.

[kivikakk]

No description provided.

[kivikakk]

/run-bench

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-23c3012	107.3 ± 8.7	104.0	151.3	1.87 ± 0.15
./bench.sh ./comrak-main	106.5 ± 1.1	104.9	109.2	1.86 ± 0.03
./bench.sh ./pulldown-cmark	57.3 ± 0.7	56.5	59.9	1.00
./bench.sh ./cmark-gfm	87.7 ± 7.8	80.6	103.4	1.53 ± 0.14
./bench.sh ./markdown-it	253.7 ± 2.5	250.0	258.7	4.43 ± 0.07

Run on Sun Oct 19 12:42:45 UTC 2025

[kivikakk]

This is neat, but belongs upstream.