Wire evdevd input devices into udev-shim and enable udev in libinput

Phase 3 input chain wiring:

udev-shim: when scheme:evdev is registered (by evdevd), probe for
event0..event7 devices and create /dev/input/eventN nodes pointing to
scheme:evdev/eventN. This bridges evdevd's evdev devices into the
/dev/input namespace that libinput and compositors expect.

libinput: remove -Dudev=false and add libudev-stub as a dependency.
The libudev-stub recipe provides libudev.so that reads from scheme:udev
(udev-shim), giving libinput a working udev enumeration path instead of
stub functions that return NULL.

Input chain is now: hardware → /scheme/input → evdevd → scheme:evdev →
udev-shim → /dev/input/eventN → libudev-stub → libinput → KWin.

local/recipes/system/udev-shim/source/src/scheme.rs

@@ -126,6 +126,42 @@ impl UdevScheme {
             ));
         }
 
+        // evdevd exposes event0(event1)(mouse), event2(touchpad) via scheme:evdev.
+        // Probe which exist and create /dev/input/eventN nodes for libinput.
+        if scheme_registered("evdev") {
+            for n in 0..8u8 {
+                let name = format!("event{n}");
+                if std::path::Path::new(&format!("/scheme/evdev/{name}")).exists() {
+                    let (devpath, kind) = match n {
+                        0 => (
+                            "/devices/platform/evdev-keyboard0",
+                            InputKind::Keyboard,
+                        ),
+                        1 => (
+                            "/devices/platform/evdev-mouse0",
+                            InputKind::Mouse,
+                        ),
+                        _ => (
+                            &*format!("/devices/platform/evdev-generic{n}"),
+                            InputKind::Generic,
+                        ),
+                    };
+                    let label = match kind {
+                        InputKind::Keyboard => "Redox Evdev Keyboard",
+                        InputKind::Mouse => "Redox Evdev Mouse",
+                        _ => "Redox Evdev Generic",
+                    };
+                    self.devices.push(DeviceInfo::new_platform_input(
+                        label,
+                        devpath,
+                        kind,
+                        "",
+                        "",
+                    ));
+                }
+            }
+        }
+
         self.assign_virtual_nodes();
 
         Ok(self.devices.len())

recipes/wip/libs/other/libinput/recipe.toml

@@ -1,4 +1,4 @@
-#TODO: needs libevdev working; udev integration is disabled so the compositor owns device discovery
+#TODO: needs libevdev working; udev integration via libudev-stub (scheme:udev)
 [source]
 tar = "https://gitlab.freedesktop.org/libinput/libinput/-/archive/1.30.2/libinput-1.30.2.tar.bz2"
 patches = ["redox.patch"]
@@ -10,9 +10,9 @@ mesonflags = [
     "-Dmtdev=false",
     "-Ddebug-gui=false",
     "-Dtests=false",
-    "-Dudev=false",
     "-Ddocumentation=false",
 ]
 dependencies = [
     "libevdev",
+    "libudev-stub",
 ]