selfhost/cmd/wcc: stamp e.type_ for N_BIN + N_UN (A.6.1.3)
Adds unifyarith / binoptype / unoptype mirroring cstage
cmd/wcc/check.c:580-596, 598-640, 642-687. Two new exprtype
arms stamp e.type_ for N_BIN and N_UN via the same
tinfofornode pattern as A.6.1.1/.2.
unifyarith: untyped+untyped (prefer float), untyped+typed
(typed via isassignable), typed+typed (typeeqast), fallback ltn.
binoptype: ptr arith (ptr±int → ptr, ptr-ptr → i64), bitwise/
arith → unifyarith, comparison + logical → bool.
unoptype: deref (resolvealias+unwrapbang then N_TPTR.lhs),
addrof → *T with slice/str pseudo-field .len/.cap widening
to *i64 (mirrors check.c:672-682), unary +/-/^/!.
Wwstage stays silent on operator-type errors per existing
checker discipline; cstage flags the same shapes.
Verified 132/132 incl. 995_self_rebuild byte-identity.
Hojun-Cho
ada99973ee