Function synthesise_generic_doc_block 

fn synthesise_generic_doc_block(
    kind: &str,
    generic: &str,
    classes: &[String],
    export: bool,
    dispatch: &str,
    no_dots: bool,
) -> String

Synthesise a standalone roxygen doc block for a generic.

Produces a block with:

• @title / @description describing the generic
• @param lines for each dispatch argument (plus ... unless no_dots)
• @name <generic> — yields the bare \alias{<generic>} that ?generic resolves
• @export or @rawNamespace export(<generic>) as appropriate
• NULL anchor

The method blocks emitted by the class generators keep their qualified @name Class-generic so there is no duplicate-alias regression.