feat(deploy): add deployment script and update Docker docs

- Add deploy.sh for automated Docker build and push to private registry
- Lowercase Docker image name to comply with registry requirements
- Update README with concrete Docker run examples and configuration

build.gradle.kts

@@ -68,8 +68,8 @@ docker {
         baseImage.set("bellsoft/liberica-runtime-container:jre-21-slim-musl")
         ports.set(listOf(8080))
         images.set(setOf(
-            "$giteaRegistry/$giteaUser/bookMgr:${project.version}",
-            "$giteaRegistry/$giteaUser/bookMgr:latest"
+            "$giteaRegistry/$giteaUser/bookmgr:${project.version}",
+            "$giteaRegistry/$giteaUser/bookmgr:latest"
         ))
         jvmArgs.set(listOf("-Xmx512m", "-Dfile.encoding=UTF-8"))
     }