test/lang: absorb retired-carrier coverage

local_zeroinit_test.ww takes the 840/944 zero-init seam (dirty-frame
prime and probe share one @test because the runtime forks per test);
alias_cgen_b6, alloc_nested_field, array_static_init, and
strarray_static gain the rows their retired wrappers held; the
remaining files re-point reject-row citations at the r788_* and
stage-matrix fixtures.

test/lang/strarray_static_test.ww

@@ -7,7 +7,8 @@
 // .len-only check would miss a wrong/swapped element relocation. The empty-slot
 // and `...` repeat-suffix rows pin that an empty element doesn't shift the
 // following element's reloc and that the repeat-fill row's DATAR resolves to the
-// last explicit element.
+// last explicit element. The under-length row separately pins that omitted
+// elements have zero-length headers rather than replaying the last string.
 
 package strarray_static_test;
 
@@ -16,6 +17,7 @@ let TPTR: [3]str = ["A", "B", "C"];
 let TVAR: [3]str = ["xx", "yyy", "z"];
 let TEMP: [2]str = ["", "Z"];
 let TREP: [3]str = ["X", "Y"...];
+let TTAIL: [4]str = ["ab", "cde"];
 
 @test fn strtab_len() void = {
 	assert((TLEN[0].len + TLEN[1].len + TLEN[2].len): i32 == 6);
@@ -42,3 +44,10 @@ let TREP: [3]str = ["X", "Y"...];
 	let p: *u8 = TREP[2].ptr;
 	assert((*p): i32 == 89);
 };
+
+@test fn strtab_zero_tail() void = {
+	assert(TTAIL[0].len == 2);
+	assert(TTAIL[1].len == 3);
+	assert(TTAIL[2].len == 0);
+	assert(TTAIL[3].len == 0);
+};