Faithful port of ref/hare/types/arch+x86_64.ha:16-26. SIZE_MAX is the
no-cast `def SIZE_MAX: size = U64_MAX;` — size is in the unsigned class
and 8B on amd64, so the u64->size init coerces without a cast (#113);
UINTPTR_MAX keeps Hare's explicit `U64_MAX: uintptr` since uintptr is
outside the unsigned class. Probe 958_types_sizelim_run asserts MIN==0,
MAX==U64_MAX, and arithmetic usability for both types.
INT_MIN/MAX + UINT_MIN/MAX deferred to #114 (ww int=8B vs Hare 4B on
amd64 leaves the value open); RUNE_MAX deferred to #112 (no \U lexer).
combined.ww regenerated for all 5 selfhost tools + smoke.combined.ww
(all embed lib/types).
Hojun-Cho
b1c598651f