fnptrcalleetfn's N_DOT arm required an N_IDENT base, so a.b.cb(...)
fell to the name registry with an empty module hint and emitted
CALL cb(SB) (undefined symbol; cstage calls the stamped ptr indirect).
dotbasestructinfo resolves the base chain through the struct registry
— each link a struct- or *struct-typed field — and the single-dot
path routes through the same resolver unchanged. Closes the last open
shape of the #59.8 name-keyed callee family. Fixture fnptrfield_chain;
corpus pin 1487/2974.