jetscii for line searcher.

[kivikakk]

We can SIMD this now.

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-5e9c73f	101.1 ± 1.3	99.3	105.3	1.70 ± 0.03
./bench.sh ./comrak-main	101.5 ± 1.8	99.7	109.3	1.71 ± 0.04
./bench.sh ./pulldown-cmark	59.5 ± 0.7	58.5	61.6	1.00
./bench.sh ./cmark-gfm	93.4 ± 7.1	84.1	105.7	1.57 ± 0.12
./bench.sh ./markdown-it	266.2 ± 3.6	259.9	274.1	4.47 ± 0.08

Run on Tue Nov 11 00:53:06 UTC 2025