test/wcc/data: grow the declarative compiler corpus to 1,224 fixtures

The r-prefixed waves absorb the runtime, reject, and byte-compare rows
of the migrated native carriers; each fixture is one directory with one
case.ww and a //ww:error, //ww:compile, //ww:run, or //ww:run-exit
directive covering both frontends.

test/wcc/data/r681_ptr_arr_dyn_idx_write/case.ww

@@ -0,0 +1,9 @@
+//ww:run-exit 99
+package main;
+type nd = struct { name: str, x: i32 };
+fn main() i32 = {
+	let a: nd; a.name = "a"; a.x = 0; let b: nd; b.name = "b"; b.x = 0;
+	let c: nd; c.name = "c"; c.x = 0; let stk: [4]*nd;
+	stk[0] = &a; stk[1] = &b; stk[2] = &c; let i: i32 = 2;
+	stk[i].x = 99; return stk[2].x;
+};