restructure: move el compiler content into lang/

lang/tests/calendar/examples/earth-zone.el

@@ -0,0 +1,16 @@
+// earth-zone.el — EarthCalendar(zone) formats with the right zone abbreviation.
+// We use a fixed Instant on July 4, 2026 (definitely EDT in NYC) so the
+// abbreviation is deterministic across runs.
+
+fn run_test() -> String {
+    let z: Zone = zone("America/New_York")
+    let cal: Calendar = earth_calendar(z)
+    // 2026-07-04 12:00:00 UTC = 2026-07-04 08:00:00 EDT
+    let i: Instant = unix_seconds(1782216000)
+    let ct: CalendarTime = in_calendar(i, cal)
+    return cal_format(ct, "z")
+}
+
+fn main() -> Void {
+    println(run_test())
+}