fix: check both systemd error messages for missing boot journal

Support both systemd error message variants for first boot detection:
- systemd 255+: 'No journal boot entry found for the specified boot'
- systemd 252: 'No such boot ID in journal'

Signed-off-by: Sarita Mahajan <sarmahaj@redhat.com>
Assisted-by: Claude (claude-sonnet-4.5)

Author: sarmahaj

src/main.rs

@@ -179,7 +179,12 @@ fn check_previous_rollback() -> Result<bool> {
     if !output.status.success() {
         let stderr = String::from_utf8_lossy(&output.stderr);
         // Check if failure is due to missing previous boot (expected on first boot)
-        if stderr.contains("No journal boot entry found for the specified boot") {
+        // Different systemd versions use different error messages:
+        // - systemd 255+ (RHEL 10.2): "No journal boot entry found for the specified boot"
+        // - systemd 252 (RHEL 9.8): "Data from the specified boot (-1) is not available: No such boot ID in journal"
+        if stderr.contains("No journal boot entry found for the specified boot")
+            || stderr.contains("No such boot ID in journal")
+        {
             log::info!(
                 "No previous boot journal available (expected on first boot or systems with non-persistent journal). Skipping rollback check."
             );