test(joinir): Phase 124 return-var normalized smoke (VM)

Phase 124-P4:
- Add fixture: apps/tests/phase124_if_only_return_var_min.hako
  - local x; x = 7; print(x); return x
  - Expected output: 7 (print), RC: 7 (return x)
- Add smoke: tools/smokes/v2/profiles/integration/apps/phase124_if_only_return_var_vm.sh
  - NYASH_JOINIR_DEV=1 HAKO_JOINIR_STRICT=1 for dev-only features
  - Accept exit code 7 (return x where x=7) as valid
- Verify all Phase 121/123/118 smokes still PASS

apps/tests/phase124_if_only_return_var_min.hako

@@ -0,0 +1,11 @@
+// Phase 124: If-only return variable minimal test
+// Expected: 7
+
+static box Main {
+    main() {
+        local x
+        x = 7
+        print(x)
+        return x
+    }
+}

tools/smokes/v2/profiles/integration/apps/phase124_if_only_return_var_vm.sh

@@ -0,0 +1,62 @@
+#!/bin/bash
+# Phase 124: If-only Return Variable (VM)
+#
+# Verifies that Return(Variable) works when variable is in env (writes):
+# - local x; x = 7; return x → generates Ret(Some(ValueId))
+# - Variable in env (writes-derived) is supported
+# - Dev-only: NYASH_JOINIR_DEV=1 HAKO_JOINIR_STRICT=1
+
+source "$(dirname "$0")/../../../lib/test_runner.sh"
+source "$(dirname "$0")/../../../lib/output_validator.sh"
+export SMOKES_USE_PYVM=0
+require_env || exit 2
+
+PASS_COUNT=0
+FAIL_COUNT=0
+RUN_TIMEOUT_SECS=${RUN_TIMEOUT_SECS:-10}
+
+echo "[INFO] Phase 124: If-only Return Variable (VM)"
+
+# Test 1: phase124_if_only_return_var_min.hako
+echo "[INFO] Test 1: phase124_if_only_return_var_min.hako"
+INPUT="$NYASH_ROOT/apps/tests/phase124_if_only_return_var_min.hako"
+
+set +e
+OUTPUT=$(timeout "$RUN_TIMEOUT_SECS" env \
+  NYASH_DISABLE_PLUGINS=1 \
+  HAKO_JOINIR_STRICT=1 \
+  NYASH_JOINIR_DEV=1 \
+  "$NYASH_BIN" --backend vm "$INPUT" 2>&1)
+EXIT_CODE=$?
+set -e
+
+if [ "$EXIT_CODE" -eq 124 ]; then
+  echo "[FAIL] hakorune timed out (>${RUN_TIMEOUT_SECS}s)"
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+elif [ "$EXIT_CODE" -eq 0 ] || [ "$EXIT_CODE" -eq 7 ]; then
+  # Phase 124: exit code 7 is OK (return x where x=7)
+  EXPECTED="7"
+  if validate_numeric_output 1 "$EXPECTED" "$OUTPUT"; then
+    echo "[PASS] Output verified: 7 (exit code: $EXIT_CODE)"
+    PASS_COUNT=$((PASS_COUNT + 1))
+  else
+    echo "[INFO] output (tail):"
+    echo "$OUTPUT" | tail -n 50 || true
+    FAIL_COUNT=$((FAIL_COUNT + 1))
+  fi
+else
+  echo "[FAIL] hakorune failed with exit code $EXIT_CODE"
+  echo "[INFO] output (tail):"
+  echo "$OUTPUT" | tail -n 50 || true
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+fi
+
+echo "[INFO] PASS: $PASS_COUNT, FAIL: $FAIL_COUNT"
+
+if [ "$FAIL_COUNT" -eq 0 ]; then
+  test_pass "phase124_if_only_return_var_vm: All tests passed"
+  exit 0
+else
+  test_fail "phase124_if_only_return_var_vm: $FAIL_COUNT test(s) failed"
+  exit 1
+fi