selfhost: introduce using-based imports for compiler/parser/tools; keep includes temporarily. llvm: add PHI wiring JSON trace + unit/integration tests; fast test suite extended. runner: split selfhost helpers, small cleanups.

tools/test/smoke/python/unit/test.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/../../../../.." && pwd)
+
+if ! command -v python3 >/dev/null 2>&1; then
+  echo "[SKIP] python unit: python3 not available"; exit 0
+fi
+
+"$ROOT/tools/python_unit.sh" >/dev/null
+echo "OK: python unit (phi_wiring helpers)"
+