test: retire 13 byteid carriers into the corpus blanket

Ten of the thirteen were already fully twinned — their runtime rows
migrated in earlier waves (r56_def_*, r79_*, r78_*, r926_*,
r989_m1union_*) and the carriers survived only for a cstage-vs-wwstage
byte-compare the blanket test-data-byteid comparator owns once the
source is a corpus fixture. The other three needed their remaining
inline sources added first: r756_* (4, alias-chain unwrap),
r844_bid_src (size(u64) untyped-int compare), r989_structframe_* (3,
struct-local frame layout). Every new fixture was verified both-stage:
compile exit 0 twice, .s byte-identical, runtime exit as pinned.

The five ww_ww-driver-leg carriers among them (785/786/789/790/
m1union) follow the 815/940/951 precedent: content identity owned by
their corpus twins, driver-leg identity owned by 989_lib_byteid's
sweep. Byte/artifact partition 24 -> 11; carriers 147 -> 134; corpus
pin 1495/2990; the stale 915 sweep figure in the docs corrected to
the true 1,157 non-error count.

test/wcc/data/r756_r1_i32_struct/case.ww

@@ -0,0 +1,16 @@
+//ww:run
+package main;
+type r1 = struct {
+	a: i32, b: i32, c: i32, d: i32, e: i32, f: i32, g: i32,
+	h: i32, i: i32, j: i32, k: i32, l: i32, m: i32, p: i32,
+};
+fn make_r1() r1 = {
+	let b: r1;
+	b.p = 99i32;
+	return b;
+};
+export fn main() i32 = {
+	let s: r1 = make_r1();
+	if (s.p != 99i32) { return 11; };
+	return 0;
+};