M12: Cargo.lock follows the 0.18.0 workspace version

The merge of main kept pdfcraft-prc at 0.17.0 in the lock file, so --locked builds failed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SqmHYx8FiWM5PcsoiErgp9

Cargo.lock

@@ -4553,7 +4553,7 @@ dependencies = [
 
 [[package]]
 name = "pdfcraft-prc"
-version = "0.17.0"
+version = "0.18.0"
 dependencies = [
  "flate2",
  "proptest",