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/r85_index_float/case.ww

@@ -0,0 +1,7 @@
+//ww:error "index must be integer"
+package main;
+fn main() i32 = {
+	let a: [3]i32 = [10i32, 20i32, 30i32];
+	let f: f64 = 1.0;
+	return a[f];
+};