[Feature] Add autologin support (#841) (closes #200)

This is the simplest change I could come up with to add working autologin, only bit I really dislike is the event but it seemed like the cleanest way without refactoring.

Co-authored-by: ferreo <harderthanfire@gmail.com>
Reviewed-on: https://codeberg.org/fairyglade/ly/pulls/841
Reviewed-by: AnErrupTion <anerruption@disroot.org>
Co-authored-by: ferreo <ferreo@noreply.codeberg.org>
Co-committed-by: ferreo <ferreo@noreply.codeberg.org>

res/config.ini

@@ -46,6 +46,30 @@ auth_fails = 10
 # If set to null, battery status won't be shown
 battery_id = null
 
+# Automatic login configuration
+# This feature allows Ly to automatically log in a user without password prompt.
+# IMPORTANT: Both auto_login_user and auto_login_session must be set for this to work.
+# Autologin only happens once at startup - it won't re-trigger after logout.
+
+# PAM service name to use for automatic login
+# The default service (ly-autologin) uses pam_permit to allow login without password
+# The appropriate platform-specific PAM configuration (ly-autologin) will be used automatically
+auto_login_service = ly-autologin
+
+# Session name to launch automatically
+# To find available session names, check the .desktop files in:
+#   - /usr/share/xsessions/ (for X11 sessions)
+#   - /usr/share/wayland-sessions/ (for Wayland sessions)
+# Use the filename without .desktop extension, or the value of DesktopNames field
+# Examples: "i3", "sway", "gnome", "plasma", "xfce"
+# If null, automatic login is disabled
+auto_login_session = null
+
+# Username to automatically log in
+# Must be a valid user on the system
+# If null, automatic login is disabled
+auto_login_user = null
+
 # Background color id
 bg = 0x00000000