fix(tests): Handle empty output as clean execution

SDKs that run but produce no output (e.g., waiting for CLI args)
should pass since the runtime executed successfully. This fixes
php and javascript sdk_runs tests that exit cleanly with no output.

scripts/test-sdk.sh

@@ -212,6 +212,14 @@ run_test() {
         return 0
     fi
 
+    # If output is empty but command didn't error, the runtime executed successfully
+    # This handles SDKs that exit cleanly without printing anything
+    if [ ! -s "$output_file" ]; then
+        TEST_RESULTS["$test_name"]="pass"
+        echo "PASS (clean exit)"
+        return 0
+    fi
+
     TEST_RESULTS["$test_name"]="fail"
     FAILURES=$((FAILURES + 1))
     echo "FAIL"