Variable bibliographyRuleConst

Block rule for Wikidot [[bibliography]]...[[/bibliography]].

Parsing strategy:

1. Match BLOCK_OPEN + block name "bibliography".
2. Parse optional attributes (title, hide).
3. Consume the closing ]] and optional newline.
4. Loop over the body, parsing each : label : content line via parseBibliographyEntry().
5. Require and consume [[/bibliography]].
6. Convert entries into DefinitionListItem format and emit a bibliography-block element.