feat: switch logging to systemd journal (v0.4.2)

Replace env_logger + /var/cache/moonlock file logging with
systemd-journal-logger. Logs are now reliably accessible via
journalctl --user -u moonlock, fixing invisible errors in the
systemd user service context.

- Cargo.toml: env_logger → systemd-journal-logger 2.2
- main.rs: setup_logging() uses JournalLog
- PKGBUILD: add systemd-libs dependency
- power.rs: include unstaged systemctl fixes (ABOUTME, --no-ask-password, output())

src/power.rs

@@ -1,4 +1,4 @@
-// ABOUTME: Power actions — reboot and shutdown via loginctl.
+// ABOUTME: Power actions — reboot and shutdown via systemctl.
 // ABOUTME: Wrappers around system commands for the lockscreen UI.
 
 use std::fmt;
@@ -22,11 +22,10 @@ impl fmt::Display for PowerError {
 impl std::error::Error for PowerError {}
 
 fn run_command(action: &'static str, program: &str, args: &[&str]) -> Result<(), PowerError> {
-    let child = Command::new(program)
+    let output = Command::new(program)
         .args(args)
-        .spawn()
-        .map_err(|e| PowerError::CommandFailed { action, message: e.to_string() })?;
-    let output = child.wait_with_output()
+        .stderr(std::process::Stdio::piped())
+        .output()
         .map_err(|e| PowerError::CommandFailed { action, message: e.to_string() })?;
     if !output.status.success() {
         let stderr = String::from_utf8_lossy(&output.stderr);
@@ -37,8 +36,8 @@ fn run_command(action: &'static str, program: &str, args: &[&str]) -> Result<(),
     Ok(())
 }
 
-pub fn reboot() -> Result<(), PowerError> { run_command("reboot", "/usr/bin/systemctl", &["reboot"]) }
-pub fn shutdown() -> Result<(), PowerError> { run_command("shutdown", "/usr/bin/systemctl", &["poweroff"]) }
+pub fn reboot() -> Result<(), PowerError> { run_command("reboot", "/usr/bin/systemctl", &["--no-ask-password", "reboot"]) }
+pub fn shutdown() -> Result<(), PowerError> { run_command("shutdown", "/usr/bin/systemctl", &["--no-ask-password", "poweroff"]) }
 
 #[cfg(test)]
 mod tests {