feat: add start-hyprland watchdog override for uwsm session

Hyprland 0.53+ requires launching via start-hyprland (watchdog) for
proper crash diagnostics and signal handling. Without it a warning
banner appears on login.

Override package-managed hyprland.desktop with local copy pointing to
start-hyprland. XDG_DATA_DIRS priority ensures the override wins
without modifying system files.

- ansible/roles/hyprland/tasks/main.yml: manage override in ~/.local/share/wayland-sessions/
- docs/adr/0004-start-hyprland-override.md: full decision record
- docs/hyprland-uwsm.md: document override behavior

ansible/roles/hyprland/tasks/main.yml

@@ -53,14 +53,23 @@
   notify: rebuild initramfs
   tags: [hyprland, nvidia]
 
-- name: Hyprland - register Wayland session desktop entry
+- name: Hyprland - override Wayland session desktop entry (local user)
+  # Overrides /usr/share/wayland-sessions/hyprland.desktop with start-hyprland
+  # as the Exec target. This ensures Hyprland is launched through the watchdog
+  # binary (start-hyprland) for proper crash diagnostics and signal handling.
+  # XDG_DATA_DIRS priority: ~/.local/share > /usr/share.
+  # See: docs/adr/0004-start-hyprland-override.md
   copy:
-    dest: /usr/share/wayland-sessions/hyprland.desktop
+    dest: /home/{{ system_user }}/.local/share/wayland-sessions/hyprland.desktop
+    owner: "{{ system_user }}"
+    group: "{{ system_user }}"
+    mode: '0644'
     content: |
       [Desktop Entry]
       Name=Hyprland
       Comment=An intelligent dynamic tiling Wayland compositor
-      Exec=Hyprland
+      Exec=start-hyprland
+      TryExec=start-hyprland
       Type=Application
       DesktopNames=Hyprland
   tags: [hyprland, session]