wcc_ww/cgen: #101 narrow-alias fill-stride via aliasprimsize SSoT

A struct-literal array fill sized a narrow-alias element off a bare
primsize(name): `type my32 = u32` gave primsize("my32")=0, so the
element width defaulted to 8 and a [3]my32 strode MOVQ -24/-16/-8 —
field n collided with arr[2] (kw1_101 run exit 1). cstage chases
my32->u32->4 (MOVL stride-4) at the twin sites and is runtime-correct;
this is a ww-only align-up, cs untouched.

Fix: a new aliasprimsize(c, nm) SSoT helper — primsize(nm), else an
aliaslookup-chase N_TNAME loop then primsize — and route the SIZE-use
primsize() family through it. The 7 c-bearing bare-no-chase size-use
sites are routed: cgen:993 (letemitsize), cgenstmt:1896 (cgarrlitfillbp),
cgenutil:1579 (elemsizeofc fallback)/1657+1665 (nodeprimwidth)/4791
(cgstructlitfill = the kw1_101 site), cgenexpr:6902 (cgcall vararg esz).
This is the rule-13 close-by-construction shape (one accessor for
"resolved primitive size"), not a per-site patch.

kw1_101 is the SOLE asm mover (byte-id NO->YES, run 1->0, MOVL
stride-4); every other routed site is latent/byte-neutral. Bootstrap:
all 5 combined units stay w6c==w6c_ww byte-identical. sizelint 0,
peellint 0, test-unit 296/296.

Scope fence (rob route-7-decline-6 ruling): three DESIGNED-exemption
sites carry inline primsize-ok annotations — elemsizeof :1475/:1499 and
paramfieldsize :3541 are structural (no-`c`, non-chasing) BY DESIGN;
their alias-chasing twin elemsizeofc is the routed :1579 leg. These are
the #109 peellint-whitelist seeds. Three further declines are already
correct chasing paths, not bare-no-chase bug shapes (typenodeprimresolved
:2026 / exprprimresolved :2063 are the chase machinery itself; cgassign
:7631 already chases via typenodeprimresolved, #11). The ~17 GUARD sites
(is-primitive dispatch) + the peellint finale are the committed #109
follow-on. Threading `c` into the structural sizers is dormant #110.

#101

selfhost/cmd/wcc/cgenexpr.ww

@@ -6899,7 +6899,7 @@ fn cgcall(c: *cgen, n: *node) void = {
 				let esz: i32 = 8;
 				if (velem != nil) {
 					if (velem.kind == nkind.N_TNAME) {
-						let ps: i32 = primsize(velem.str);
+						let ps: i32 = aliasprimsize(c, velem.str);
 						if (ps > 0) { esz = ps; }
 						else { esz = slotsize(c, velem); };
 					} else {