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/r702_deref_write_str/case.ww

@@ -0,0 +1,4 @@
+//ww:run-exit 42
+package main;
+type box = struct { s: str, n: i64 };
+fn main() i32 = { let v: box; let p: *box = &v; (*p).s = "hi"; (*p).n = 40i64; return (v.s.len: i64 + v.n): i32; };