v0.1.368 — sum/min/max over a tuple (PMAT-669)

Correctness (PMAT-669): sum(t) / min(t) / max(t) over a fixed-arity tuple now work (e.g. sum((3, 7, 2)) → 12) instead of emitting an undefined sum(t) free call (E0425). A tuple is iterable in Python; the builtin argument-materializer now treats a tuple as a list of its elements (a literal uses its elements directly; a variable indexes each field). The shared materializer makes sum/min/max over a homogeneous tuple all work. Found by the HUNT-V5 differential hunt; verified vs python3. 426 e2e fixtures.