One entry inside an Item::List. inlines is the item’s own
text (markers stripped, parsed with the same inline tokenizer as
paragraphs); children carries nested blocks, currently restricted
to further Item::Lists per the MVP scope.
Output of crate::parse. Diagnostics may include warnings even
when the tree is structurally usable; callers decide what to do per
ParseResult::has_errors.
Tag for the directive shapes Item::Set can represent: the
#set <target>(...) configuration directive vs the standalone
#image(...), #figure(...), and #bibliography(...) calls. The
lowerer dispatches on this rather than the Item::Set::name string
so #set image(...) can never collide with #image(...).
One argument inside a directive body: either a key: value
pair (the only form #set accepts) or a positional value (a
leading string literal allowed on #image(...) / #figure(...)).
Literal values recognised inside a #set body. Full expression
evaluation (#let, function calls, if) is deferred to MVP 5; this
covers what the manifest examples actually use.