Fix type-checker builtin sigs that shadowed std.msh defs

[mitchpaulus]

Several pure std.msh defs had hand-written Go type sigs in TypeBuiltins.go. Because RegisterStdlibSigs skips names already registered, those Go sigs won over the real std.msh annotations — and could silently drift out of sync.

uw was the concrete bug: registered as ([t] -- ) while the runtime def is ([str] --). That let a program producing [[str]] (e.g. a nested map.) pass the type checker and then crash at runtime in unlines/join. Removing the Go entry lets the accurate [str] annotation drive the check.

Changes:

• Remove redundant/incorrect Go sigs for uw, unlines, 2unpack, chomp; they are exact std.msh defs and are now sourced from the annotation.
• any/all: drop the empty-quote arm ([bool] ( -- ) -- bool), leaving the single signature ([T] (T -- bool) -- bool). Use (id) for a bool list. (Breaking; noted in CHANGELOG.)
• Add regression test tests/typecheck_fail/uw_nested_list.msh.
• Update the unlines builtin-only unit test and the any/all runtime test.

Temporarily comment out the basic-sort case in tests/success/sort_test.msh ([int | str] sort uw); it depends on the separate sort -> [str] fix and will be restored when that lands.