self-review fixes: raise Lombok to 1.18.48, drop stale Checkstyle version, add README lead sentence

Lombok added lombok.checkReturnValueAnnotation in 1.18.48, so the new
lombok.config line had no effect on 1.18.46. The checkstyle version entry
had no remaining reference. The README Setup heading lost its lead sentence
when the registry section was removed.

Author: ThoSap

README.md

@@ -222,6 +222,8 @@ To build the project, the following prerequisites must be met:
 
 ### Setup
 
+Build the project with:
+
 ```bash
 make init
 

gradle/libs.versions.toml

@@ -5,14 +5,13 @@ axionReleasePlugin = "1.21.1"
 ## Libraries ##
 jooq = "3.21.4"
 jSpecify = "1.0.0"
-lombok = "1.18.46"
+lombok = "1.18.48"
 postgresql = "42.7.11"
 quarkiverse-helm = "1.4.0"
 scram-client = "3.2"
 
 ## Testing ##
 assertj = "3.27.7"
-checkstyle = "13.4.2"
 datafaker = "2.5.4"
 errorProne = "2.50.0"
 errorPronePlugin = "5.1.1"