Give content ownership to inline processor; pre-process entity data for binary search.

[kivikakk]

The benchmark includes no entities whatsoever, so this doesn't factor, but it's a bit of a miss to be doing a linear search on an array which contains many items we can literally never match!

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-d9abf2f	108.9 ± 0.8	107.6	111.4	1.87 ± 0.09
./bench.sh ./comrak-main	112.0 ± 1.4	109.6	115.6	1.92 ± 0.10
./bench.sh ./pulldown-cmark	58.2 ± 2.9	56.7	76.7	1.00
./bench.sh ./cmark-gfm	86.6 ± 7.2	81.0	106.3	1.49 ± 0.14
./bench.sh ./markdown-it	260.6 ± 2.3	255.9	265.8	4.48 ± 0.22

Run on Sun Oct 19 04:45:12 UTC 2025