test(cashc): add blake3 coverage; drop orphaned v2_test example

blake3 had no test coverage anywhere in the suite. Add a corpus fixture and a
focused codegen regression test, mirroring the multiplication.cash /
arithmetic.test.ts precedent:

- test/valid-contract-files/blake3.cash — exercised by the globbing
  compiler.test.ts (compiles cleanly) and AST.test.ts (parse round-trip)
- test/generation/blake3.test.ts — asserts `blake3(...)` lowers to OP_BLAKE3
  and stays distinct from `sha256(...)` / OP_SHA256

Remove examples/v2_test.rad: an unreferenced, single-commit V2 smoke test on
the deprecated `function` method syntax that also used bitwise `<<` (now
rejected on Radiant). Its `*`->OP_MUL behavior is already covered by
generation/arithmetic.test.ts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: TheArtofSatoshi

examples/v2_test.rad

@@ -0,0 +1,54 @@
+/*   blake3.test.ts
+ *
+ * Coverage + regression test: the `blake3(...)` builtin must lower to its own
+ * OP_BLAKE3 opcode and must stay DISTINCT from `sha256(...)` (OP_SHA256).
+ * blake3 previously had no test coverage anywhere in the suite. See
+ * ast/Globals.ts (GlobalFunction.BLAKE3) and generation/utils.ts
+ * (GlobalFunction.BLAKE3 -> [OP_BLAKE3]).
+ */
+
+import { compileString } from '../../src/index.js';
+
+// blake3 only — must emit OP_BLAKE3 and must NOT be aliased to OP_SHA256.
+const blake3Only = `
+pragma radiantscript ^1.1.0;
+contract Blake3Only(bytes32 commitment) {
+  return {
+    reveal(bytes preimage) {
+      require(blake3(preimage) == commitment);
+    }
+  };
+}
+`;
+
+// blake3 + sha256 over the same preimage — proves the two builtins lower to
+// distinct opcodes (both must appear in the output).
+const blake3AndSha256 = `
+pragma radiantscript ^1.1.0;
+contract Blake3Mixed(bytes32 commitment) {
+  return {
+    reveal(bytes preimage) {
+      require(blake3(preimage) == commitment);
+      require(blake3(preimage) != sha256(preimage));
+    }
+  };
+}
+`;
+
+describe('BLAKE3 hashing lowering', () => {
+  it('lowers `blake3(...)` to OP_BLAKE3', () => {
+    const asm: string = (compileString(blake3Only) as { asm: string }).asm;
+    expect(asm).toContain('OP_BLAKE3');
+  });
+
+  it('does not alias blake3 to OP_SHA256', () => {
+    const asm: string = (compileString(blake3Only) as { asm: string }).asm;
+    expect(asm).not.toContain('OP_SHA256');
+  });
+
+  it('lowers blake3 and sha256 to distinct opcodes', () => {
+    const asm: string = (compileString(blake3AndSha256) as { asm: string }).asm;
+    expect(asm).toContain('OP_BLAKE3');
+    expect(asm).toContain('OP_SHA256');
+  });
+});

packages/cashc/test/generation/blake3.test.ts

@@ -0,0 +1,8 @@
+contract Blake3Commit(bytes32 commitment) {
+    return {
+        reveal(bytes preimage) {
+            // The revealed preimage must hash (BLAKE3) to the committed digest.
+            require(blake3(preimage) == commitment);
+        }
+    }
+}