added service and timer files, aswell as Arch PKGBUILD

updated version in main.cpp to be a dependency from cmake

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required(VERSION 3.31)
 project(home_lab_watchdog_keepalive)
 
+add_definitions(-DVERSION=${VERSION})
+
 set(CMAKE_CXX_STANDARD 20)
 
 add_executable(home_lab_watchdog_keepalive main.cpp