Set plugin version to chylex-53

Fixes multiple cursors with vim-surround commands `cs, ds, S` (but not `ys`).

build.gradle.kts

@@ -303,6 +303,11 @@ tasks {
       }
     })
   }
+
+  buildPlugin {
+    dependsOn(sourcesJar)
+    from(sourcesJar) { into("lib/src") }
+  }
 }
 
 java {
@@ -375,7 +380,13 @@ intellijPlatform {
     )
 
     ideaVersion {
-      sinceBuild.set("2025.3")
+      // Let the Gradle plugin set the since-build version. It defaults to the version of the IDE we're building against
+      // specified as two components, `{branch}.{build}` (e.g., "241.15989"). There is no third component specified.
+      // The until-build version defaults to `{branch}.*`, but we want to support _all_ future versions, so we set it
+      // with a null provider (the provider is important).
+      // By letting the Gradle plugin handle this, the Plugin DevKit IntelliJ plugin cannot help us with the "Usage of
+      // IntelliJ API not available in older IDEs" inspection. However, since our since-build is the version we compile
+      // against, we can never get an API that's newer - it would be an unresolved symbol.
       untilBuild.set(provider { null })
     }
   }