A rewrite of the internals behind an unchanged template API. Extraction moved
out of Parser into Extractors/{Bard,Html,Markdown} behind one interface chosen
by an explicit Detector; the tag and the modifier read their anchors from one
registry instead of each running its own slug pass; options live in one
immutable object instead of two mutable level fields recomputed from each other.

Requires PHP 8.2 and Statamic 5 or 6. Statamic 3 and 4 stay on the 1.x branch.

Breaking: {{ toc:count }} counts what the list shows instead of forcing depth 6.
See UPGRADE.md.