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_i8_signed_write/case.ww

@@ -0,0 +1,8 @@
+//ww:run-exit 42
+package main;
+type nd = struct { tag: i8, pad: u8, x: i32 };
+fn main() i32 = {
+	let v: nd; v.tag = 0i8; v.pad = 0u8; v.x = 0;
+	let stk: [4]*nd; stk[0] = &v; stk[0].tag = -3i8;
+	let t: i32 = stk[0].tag: i32; if (t == -3) { return 42; }; return 0;
+};