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.c

@@ -0,0 +1,12 @@
+#include "wifi_auth.h"
+
+/* TODO: modal dialog with password entry + "remember" checkbox.
+ *       Bound to the iwd Agent's RequestPassphrase reply. */
+
+void
+wifi_auth_prompt(Evas_Object *parent EINA_UNUSED,
+                 const char *ssid EINA_UNUSED,
+                 Wifi_Auth_Cb cb EINA_UNUSED,
+                 void *data EINA_UNUSED)
+{
+}