fix: WASM smoke test — verify compilation only, skip wasmtime

GHC's WASM backend produces binaries with ghc_wasm_jsffi imports (from
ghc-internal's Wasm.Prim.Types), requiring a JavaScript host environment
(Node.js + GHC WASM runtime shim). Plain wasmtime can't satisfy these
imports. Compilation + linking is sufficient to validate the cross-build.

Author: angerman

.github/workflows/nix-ci.yml

@@ -829,14 +829,13 @@ jobs:
         export PATH=$PATH:$HOME/.ghc-wasm/wasi-sdk/bin
         echo 'main = putStrLn "Hello from WASM backend"' > /tmp/hello.hs
         _build/dist/bin/wasm32-unknown-wasi-ghc /tmp/hello.hs -o /tmp/hello.wasm
-        # Run with wasmtime if available (ghc-wasm-meta may install it
-        # under different paths depending on FLAVOUR)
-        WASMTIME=$(find $HOME/.ghc-wasm -name wasmtime -type f 2>/dev/null | head -1)
-        if [[ -n "$WASMTIME" ]]; then
-          "$WASMTIME" /tmp/hello.wasm
-        else
-          echo "wasmtime not found, skipping runtime test (compilation succeeded)"
-        fi
+        # Verify the .wasm binary was produced. Runtime execution requires
+        # JavaScript FFI glue (ghc_wasm_jsffi imports from ghc-internal),
+        # so plain wasmtime can't run it — would need Node.js + GHC WASM
+        # runtime shim. Compilation + linking is sufficient to validate
+        # the cross-build.
+        ls -lh /tmp/hello.wasm
+        file /tmp/hello.wasm
 
     - name: Upload WASM cross artifacts
       uses: actions/upload-artifact@v4