A package-less primary's bare fn (module="") whose leaf collided with an
imported module's same-leaf exported fn was mis-mangled to the imported
qualified name (a user `fn run` emitted as `test.run`), producing a
dead-duplicate symbol the linker silently shadowed -- a #263-class silent
miscompile, gate-blind and symmetric across both stages. cgen now registers
bare-module fns and resolves a bare-ident reference to its own bare leaf:
mod_lookup_for_fn prefers the bare entry when the call carries no module
hint and skips bare entries when it does, so the moduled-caller path stays
byte-identical. The moduled `main` entry carve-out is an orthogonal rule
(the linker entry is force-bared) and is retained. Prereq for the @test
user-`run` coexist (#80). The bare non-fn (let/def/type) sibling is the
same class but hint-less; deferred as #85, noted at the retained skip.
Hojun-Cho
08cfb5b2dd