fix: kded6 wrapper script — definitive Qt6 Wayland crash prevention

kded6 wrapper (/usr/bin/kded6 → kded6-wrapper.sh → kded6.real):
- Sets QT_QPA_PLATFORM=offscreen before executing real kded6
- Works regardless of launch mechanism (init, D-Bus, direct)
- No dependency on #ifdef Q_OS_REDOX, D-Bus Environment=, or build cache
- kded6 is a headless D-Bus daemon — Wayland adds no functionality

redox.patch: added null guards to wayland-client.c (wl_proxy_add_listener,
wl_proxy_get_version, wl_proxy_get_display) — durable patch for when
libwayland build is fixed.

local/patches/libwayland/redox.patch

@@ -37,3 +37,31 @@
  #include <sys/file.h>
  #include <sys/stat.h>
  
+@@ -649,6 +649,11 @@
+ wl_proxy_add_listener(struct wl_proxy *proxy,
+ 		      void (**implementation)(void), void *data)
+ {
++	if (!proxy) {
++		fprintf(stderr, "FATAL: wl_proxy_add_listener(NULL) caller=%p -- returning error\n",
++		        __builtin_return_address(0));
++		return -1;
++	}
+ 	if (proxy->flags & WL_PROXY_FLAG_WRAPPER)
+ 		wl_abort("Proxy %p is a wrapper\n", proxy);
+ 
+@@ -2442,6 +2447,7 @@
+ WL_EXPORT uint32_t
+ wl_proxy_get_version(struct wl_proxy *proxy)
+ {
++	if (!proxy) return 0;
+ 	return proxy->version;
+ }
+ 
+@@ -2560,6 +2566,7 @@
+ WL_EXPORT struct wl_display *
+ wl_proxy_get_display(struct wl_proxy *proxy)
+ {
++	if (!proxy) return NULL;
+ 	return proxy->display;
+ }
+ 

local/recipes/kde/kf6-kded6/recipe.toml

@@ -39,6 +39,14 @@ cmake "${COOKBOOK_SOURCE}" \
 cmake --build . -j${COOKBOOK_MAKE_JOBS}
 DESTDIR="${COOKBOOK_STAGE}" cmake --install . --prefix /usr
 
+# Prevent Qt6 Wayland crash on Redox: wrap kded6 with QT_QPA_PLATFORM=offscreen.
+# kded6 is a headless D-Bus daemon — Wayland is unnecessary.
+if [ -f "${COOKBOOK_STAGE}/usr/bin/kded6" ]; then
+    mv "${COOKBOOK_STAGE}/usr/bin/kded6" "${COOKBOOK_STAGE}/usr/bin/kded6.real"
+    cp "${COOKBOOK_SOURCE}/kded6-wrapper.sh" "${COOKBOOK_STAGE}/usr/bin/kded6"
+    chmod +x "${COOKBOOK_STAGE}/usr/bin/kded6"
+fi
+
 for lib in "${COOKBOOK_STAGE}/usr/lib/"libKF6*.so.*; do
     [ -f "${lib}" ] || continue
     patchelf --remove-rpath "${lib}" 2>/dev/null || true

local/recipes/kde/kf6-kded6/source/kded6-wrapper.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# kded6 wrapper — prevents Qt6 Wayland QPA crash on Redox
+# Qt6 Wayland page-faults at null+8 during wl_proxy_add_listener.
+# kded6 is a headless D-Bus daemon; Wayland is unnecessary.
+export QT_QPA_PLATFORM=offscreen
+exec /usr/bin/kded6.real "$@"