fix(intel-ipu7-camera): fix service enable, remove broken PipeWire browser flags

- Replace su - with systemctl --global enable + runuser; su - fails silently
  in pacman install scripts, leaving camera-feed-watch.service disabled
- Remove _add_pipewire_camera(): adding PipeWireCamera/WebRtcPipeWireCamera
  to browser flags routes camera through PipeWire which is non-functional for
  this setup; V4L2 direct access to /dev/video50 works correctly
- Fix disable-libcamera.conf: replace broken /dev/null script override with
  correct WirePlumber 0.5 wireplumber.profiles syntax

Closes #56

pkgbuilds/edge/intel-ipu7-camera/disable-libcamera.conf

@@ -1,16 +1,6 @@
-# Disable libcamera monitor - make it a no-op to prevent crash
-# Camera is provided via v4l2loopback + icamerasrc instead
-wireplumber.components.rules = [
-  {
-    matches = [
-      {
-        name = "monitors/libcamera/enumerate-device.lua"
-      }
-    ]
-    actions = {
-      override = {
-        name = /dev/null, type = script/lua
-      }
-    }
+# Disable libcamera monitor - camera is provided via v4l2loopback + icamerasrc instead
+wireplumber.profiles = {
+  main = {
+    "monitor.libcamera" = disabled
   }
-]
+}