Phase 0: scaffold e_iwd Enlightenment module

Meson build, module entry points, and stub layout for the iwd backend
(D-Bus client, gadget, popup, config, UI widgets). Bodies are TODOs;
this compiles against EFL/E headers but performs no D-Bus work yet.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ui/wifi_auth.h

@@ -0,0 +1,11 @@
+#ifndef WIFI_AUTH_H
+#define WIFI_AUTH_H
+
+#include <Elementary.h>
+
+typedef void (*Wifi_Auth_Cb)(void *data, const char *passphrase, Eina_Bool remember);
+
+void wifi_auth_prompt(Evas_Object *parent, const char *ssid,
+                      Wifi_Auth_Cb cb, void *data);
+
+#endif