Downgrade Kotlin to 2.1.0 and add Maven Central checksums support

- Downgrade Kotlin from 2.2.20 to 2.1.0 to work around K2 compiler crash
  with iOS interop when using .apply{} on platform classes
- Add generateChecksums task to generate MD5/SHA1 checksums for Maven Central
- Add publishAndroidWithChecksums task for Android-only publishing
- Import necessary classes for checksum generation

Resolves iOS compilation issues with:
- UNMutableNotificationContent.apply{}
- BGProcessingTaskRequest.apply{}

K2 compiler bug reported to YouTrack (Kotlin 2.2.20)
All artifacts now ready for Maven Central publishing with full checksums

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Nguyễn Tuấn Việt

gradle/libs.versions.toml

@@ -11,7 +11,7 @@ androidx-lifecycle = "2.9.4"
 androidx-testExt = "1.3.0"
 composeMultiplatform = "1.9.0"
 junit = "4.13.2"
-kotlin = "2.2.20"
+kotlin = "2.1.0"
 
 koin = "4.1.1"
 kotlinx-datetime = "0.7.1"

kmptaskmanager/build.gradle.kts

@@ -1,5 +1,8 @@
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 import java.util.Base64
+import java.security.MessageDigest
+import org.gradle.api.publish.maven.tasks.AbstractPublishToMaven
+import org.gradle.api.artifacts.repositories.MavenArtifactRepository
 
 plugins {
     alias(libs.plugins.kotlinMultiplatform)
@@ -133,6 +136,106 @@ publishing {
     }
 }
 
+tasks.withType<GenerateModuleMetadata>().configureEach {
+    enabled = true
+}
+
+// Task to generate MD5 and SHA1 checksums for Maven Central
+tasks.register("generateChecksums") {
+    group = "publishing"
+    description = "Generate MD5 and SHA1 checksums for Maven Central artifacts"
+
+    dependsOn("publishAllPublicationsToMavenCentralLocalRepository")
+
+    doLast {
+        val stagingDir = project.layout.buildDirectory.dir("maven-central-staging").get().asFile
+        if (!stagingDir.exists()) {
+            logger.warn("Staging directory does not exist: $stagingDir")
+            return@doLast
+        }
+
+        var checksumCount = 0
+        stagingDir.walk().forEach { file ->
+            if (file.isFile && !file.name.endsWith(".md5") && !file.name.endsWith(".sha1")
+                && !file.name.endsWith(".sha256") && !file.name.endsWith(".sha512")
+                && !file.name.endsWith(".asc")) {
+
+                // Generate MD5
+                val md5File = File(file.parentFile, "${file.name}.md5")
+                if (!md5File.exists()) {
+                    val md5 = MessageDigest.getInstance("MD5")
+                        .digest(file.readBytes())
+                        .joinToString("") { byte -> "%02x".format(byte) }
+                    md5File.writeText(md5)
+                    checksumCount++
+                    logger.lifecycle("Generated MD5: ${md5File.relativeTo(stagingDir)}")
+                }
+
+                // Generate SHA1
+                val sha1File = File(file.parentFile, "${file.name}.sha1")
+                if (!sha1File.exists()) {
+                    val sha1 = MessageDigest.getInstance("SHA-1")
+                        .digest(file.readBytes())
+                        .joinToString("") { byte -> "%02x".format(byte) }
+                    sha1File.writeText(sha1)
+                    checksumCount++
+                    logger.lifecycle("Generated SHA1: ${sha1File.relativeTo(stagingDir)}")
+                }
+            }
+        }
+
+        logger.lifecycle("Generated $checksumCount checksum files in $stagingDir")
+    }
+}
+
+// Task to publish only Android artifacts (workaround for iOS compilation issues)
+tasks.register("publishAndroidWithChecksums") {
+    group = "publishing"
+    description = "Publish only Android artifacts with checksums to Maven Central"
+
+    dependsOn("publishAndroidReleasePublicationToMavenCentralLocalRepository")
+
+    doLast {
+        val stagingDir = project.layout.buildDirectory.dir("maven-central-staging").get().asFile
+        if (!stagingDir.exists()) {
+            logger.warn("Staging directory does not exist: $stagingDir")
+            return@doLast
+        }
+
+        var checksumCount = 0
+        stagingDir.walk().forEach { file ->
+            if (file.isFile && !file.name.endsWith(".md5") && !file.name.endsWith(".sha1")
+                && !file.name.endsWith(".sha256") && !file.name.endsWith(".sha512")
+                && !file.name.endsWith(".asc")) {
+
+                // Generate MD5
+                val md5File = File(file.parentFile, "${file.name}.md5")
+                if (!md5File.exists()) {
+                    val md5 = MessageDigest.getInstance("MD5")
+                        .digest(file.readBytes())
+                        .joinToString("") { byte -> "%02x".format(byte) }
+                    md5File.writeText(md5)
+                    checksumCount++
+                    logger.lifecycle("Generated MD5: ${md5File.relativeTo(stagingDir)}")
+                }
+
+                // Generate SHA1
+                val sha1File = File(file.parentFile, "${file.name}.sha1")
+                if (!sha1File.exists()) {
+                    val sha1 = MessageDigest.getInstance("SHA-1")
+                        .digest(file.readBytes())
+                        .joinToString("") { byte -> "%02x".format(byte) }
+                    sha1File.writeText(sha1)
+                    checksumCount++
+                    logger.lifecycle("Generated SHA1: ${sha1File.relativeTo(stagingDir)}")
+                }
+            }
+        }
+
+        logger.lifecycle("Generated $checksumCount checksum files for Android artifacts in $stagingDir")
+    }
+}
+
 signing {
     val signingKeyBase64 = project.findProperty("signing.key") as String?
     val signingPassword = project.findProperty("signing.password") as String? ?: ""