fix: kotlinx-serialization version mismatch

[ovitrif]

Summary

• Upgrade Kotlin from 1.9.20 to 2.2.0 for compatibility with consuming apps using Kotlin 2.x
• Upgrade kotlinx-serialization-json from 1.6.0 to 1.9.0 (required for Kotlin 2.2 compatibility)
• Upgrade kotlinx-coroutines-core from 1.6.4 to 1.10.2
• Upgrade atomicfu from 0.23.1 to 0.27.0
• Add serialization support to JVM bindings for parity with Android

Problem

bitkit-android uses Kotlin 2.2.21, but ldk-node was using Kotlin 1.9.20 with kotlinx-serialization 1.6.0. This caused NoSuchMethodError when trying to serialize Event objects due to version incompatibility.

kotlinx-serialization 1.6.x is only compatible with Kotlin 1.9.x. For Kotlin 2.2.x, we need kotlinx-serialization 1.9.x.

Solution

Upgrade all Kotlin-related dependencies to versions compatible with Kotlin 2.2.x:

Dependency	Before	After
Kotlin	1.9.20	2.2.0
kotlinx-serialization-json	1.6.0	1.9.0
kotlinx-coroutines-core	1.6.4	1.10.2
atomicfu	0.23.1	0.27.0

JVM Bindings Updates

• Added uniffi-jvm.toml config with generate_serializable_types = true and generate_immutable_records = true
• Updated uniffi_bindgen_generate_kotlin.sh to use gobley-uniffi-bindgen (same as Android)
• Added kotlinx-serialization-json and atomicfu dependencies to JVM build.gradle.kts
• Updated Gradle wrapper to 8.0 (required for Kotlin 2.2.0)
• Refactored JVM tests to use .copy() for immutable data class modifications

Files Changed

• uniffi-jvm.toml (new) - JVM binding generation config
• scripts/uniffi_bindgen_generate_kotlin.sh - Use gobley with config
• bindings/kotlin/ldk-node-jvm/lib/build.gradle.kts - Dependencies update
• bindings/kotlin/ldk-node-jvm/gradle/wrapper/gradle-wrapper.properties - Gradle 8.0
• bindings/kotlin/ldk-node-jvm/lib/src/test/kotlin/.../LibraryTest.kt - Use .copy()
• bindings/kotlin/ldk-node-android/build.gradle.kts - Kotlin 2.2.0
• bindings/kotlin/ldk-node-android/lib/build.gradle.kts - Dependencies update

Test plan

• Build Android bindings: cd bindings/kotlin/ldk-node-android && ./gradlew build
• Build JVM bindings: cd bindings/kotlin/ldk-node-jvm && ./gradlew build -x test
• Verify JVM bindings have 113 @Serializable annotations
• Test in bitkit-android

Release

• Release v0.7.0-rc.17