restructure: move el compiler content into lang/

lang/tests/calendar/runner.el

@@ -0,0 +1,13 @@
+// runner.el — entry point for the calendar/ acceptance corpus.
+//
+// Each calendar/examples/*.el is its own El program with its own fn main().
+// Compile, link, and run-output-diff is handled by tests/calendar/run.sh —
+// this file is the El-side stub kept for pattern parity.
+//
+// Run from the calendar/ directory:
+//   ./run.sh
+
+fn main() -> Void {
+    println("calendar/ acceptance corpus is driven by run.sh — invoke that directly.")
+    println("Each examples/*.el is a self-contained program; runner.el is a parity stub.")
+}