Replace ktlint with Spotless for code formatting

- Add Spotless plugin 8.1.0 with ktlint 1.7.1 and Google Java Format
- Configure ktlint rules, disable filename/max-line-length/property-naming
- Remove old ktlint plugin

build.gradle.kts

@@ -7,7 +7,7 @@ plugins {
     id("com.github.triplet.play") version "3.13.0" apply false
     id("org.jetbrains.kotlin.plugin.compose") version "2.2.0" apply false
     id("org.jetbrains.kotlin.plugin.serialization") version "2.2.0" apply false
-    id("org.jlleitschuh.gradle.ktlint") version "13.1.0" apply false
+    alias(libs.plugins.spotless) apply false
     id("io.gitlab.arturbosch.detekt") version "1.23.8"
 }