restructure: move el compiler content into lang/

lang/elc-cli.el

@@ -0,0 +1,7 @@
+// elc-cli.el — entry point for the self-hosted el compiler.
+//
+// All logic lives in el-compiler/src/compiler.el (which defines fn main()).
+// Importing it pulls in compiler.el + parser + lexer + codegen transitively.
+// The native compiler resolves imports textually and folds fn main() into
+// C's int main(), so this file does not declare any top-level work itself.
+import "el-compiler/src/compiler.el"