[WIP] Break down the `src/main.rs` file

- [ ] Analyze the current `src/main.rs` structure and identify logical groups - [ ] Create `src/setup.rs` module for initialization and environment setup logic - [ ] Create `src/commands.rs` module for CLI command handling - [ ] Create `src/event_loop.rs` module for event loop initialization and wayland setup - [ ] Move logging setup to `src/logging.rs` module - [ ] Move systemd integration to `src/systemd.rs` module - [ ] Update main.rs to use the new modules with minimal changes - [ ] Test the refactored code compiles and works correctly <!-- START COPILOT CODING AGENT SUFFIX --> <!-- START COPILOT CODING AGENT TIPS --> --- ✨ Let Copilot coding agent [set things up for you](https://github.com/nferhat/fht-compositor/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo.