The back end emitted a direct Janet call (f args) for every :var/:local callee,
but Janet calling a pvec-table does get (no integer key -> nil), a keyword does
the wrong thing, etc. — so (let [v [1 2 3]] (v 0)), a keyword/meta-vector in a
binding, all returned nil in compile mode (interpret was fine). Now a direct call
is emitted only when the callee is provably a function: :fn / :host always, and a
:var whose current root is a function; everything else routes through jolt-call,
which dispatches IFn correctly (function fast-path first). User/core fn calls stay
direct, so no hot-path regression — fixpoint stage1==stage2==stage3 holds.
Conformance 218/218 all modes; full suite green. Spec cases added.
0878c803d7