Add the int/uint/size entry points (ref/hare/strconv/stoi.ha:53,
stou.ha:107,113). Hare clamps to types::INT_MIN/MAX, UINT_MAX, SIZE_MAX
via stoiminmax/stoumax; ww's int/uint/size are 8B machine words
(INT/UINT/SIZE limits == I64/U64 per lib/types/types.ww:30-37), so the
clamp is a no-op — the full i64/u64 range parses with no spurious
overflow. Documented at-site (the bound consts are package-private, so
inlining them would just re-encode I64/U64_MAX).
Tests: extend inttest.ww with test_stoi_stou_stoz — value path, sign,
overflow pass-through, and the no-clamp fidelity (I64_MAX/U64_MAX parse
without overflow) plus hex/bin bases through the shared parseint core.
combined.ww regen: w6c + wwdump main.combined.ww.