fix: Improve upgrade error detection, three-way merge, and UI alignment (v5)

Author: draphy

VERSION

@@ -1 +1 @@
-4
+5

update.sh

@@ -451,8 +451,8 @@ do_version_upgrade() {
     # Use PIPESTATUS to capture dnf exit code, not tee's
     sudo dnf system-upgrade download --releasever="$target_version" -y 2>&1 | tee "$download_output"
     if [ "${PIPESTATUS[0]}" -ne 0 ]; then
-        # Check if version doesn't exist
-        if grep -qi "unable to find.*releasever\|no such.*version\|not found" "$download_output" 2>/dev/null; then
+        # Check if version doesn't exist (catch 404 errors, missing repos, etc.)
+        if grep -qiE "unable to find.*releasever|no such.*version|not found|status code: 404|Failed to download metadata|Cannot prepare internal mirrorlist" "$download_output" 2>/dev/null; then
             print_error "Fedora $target_version is not available yet."
             print_info "This version may not be released or may not be supported for upgrade."
             echo ""
@@ -483,7 +483,7 @@ do_version_upgrade() {
             # Use PIPESTATUS to capture dnf exit code, not tee's
             sudo dnf system-upgrade download --releasever="$target_version" --allowerasing -y 2>&1 | tee "$download_output"
             if [ "${PIPESTATUS[0]}" -ne 0 ]; then
-                if grep -qi "unable to find.*releasever\|no such.*version\|not found" "$download_output" 2>/dev/null; then
+                if grep -qiE "unable to find.*releasever|no such.*version|not found|status code: 404|Failed to download metadata|Cannot prepare internal mirrorlist" "$download_output" 2>/dev/null; then
                     print_error "Fedora $target_version is not available."
                     rm -f "$download_output"
                     return