Function value_block 

pub fn value_block(e: &Expr) -> Block

v0.118: wrap a single expression as a { tail: e } block, so a stub value can be type-checked or lowered in the same op-body position a provider operation’s tail occupies.

Dual-use (found during P5.4’s move, not in the original slice plan): stub_value_typechecks (in this module) uses it for the checking path; bynk-emit’s lower_stub_value_block also calls it, qualified, to lower a stub RHS value in the same op-body tail position. pub for that second caller, same as every other dual-use function in this module.