Koin and KoinApplication implement AutoCloseable

[lidonis]

Summary

• Koin and KoinApplication now implement AutoCloseable, enabling Kotlin's use { } pattern for safe resource cleanup
• close() already existed with the right signature on both classes, so the only change is adding the interface declaration and override modifier
• This is a source-compatible and binary-compatible change with no behavioral differences

Motivation

Koin's Koin and KoinApplication have close() methods but don't implement AutoCloseable. This means developers can't use Kotlin's use { } pattern and must rely on manual try/finally blocks, which is error-prone.

With this change:

koinApplication {
    modules(myModule)
}.use { app ->
    val service: MyService = app.koin.get()
    // work with service
}
// app.close() called automatically, even on exceptions

This is the same pattern Kotlin developers use for InputStream, Connection, ResultSet, etc. Koin instances hold resources and have a lifecycle, so they belong in this family.

This is a companion to #2363, which added AutoCloseable to Scope.

Changes

• Koin.kt: Added AutoCloseable interface and override on close()
• KoinApplication.kt: Added AutoCloseable interface and override on close()
• KoinAutoCloseableTest.kt: Four tests verifying use { } works and closes on exceptions for both classes
• start-koin.md / starting-koin.md: Updated documentation with use { } examples

Compatibility

• Source compatible: existing code compiles without changes
• Binary compatible: adding an interface is ABI-safe
• Behavioral: no change, close() already exists with identical semantics
• Multiplatform: AutoCloseable is available in kotlin.stdlib for all targets since Kotlin 1.8

Test plan

• Koin implements AutoCloseable and works with use verifies use { } resolves instances and auto-closes
• Koin use closes on exception verifies close is called even when an exception is thrown
• KoinApplication implements AutoCloseable and works with use verifies use { } resolves instances and auto-closes
• KoinApplication use closes on exception verifies close is called even when an exception is thrown