Fix #2416 - refresh closed Koin context in Compose

[AvikMakwana]

Problem

getKoin() could return a stale Koin instance after a stopKoin() / startKoin() cycle.

LocalKoinApplicationContext caches the first Koin instance through ComposeContextWrapper. After that instance is closed, getKoin() still returned the cached value because getValue() itself succeeded, so the existing exception recovery path was never reached.

Dependency resolution then failed with:

ClosedScopeException: Scope '_root_' is closed

Fix

getKoin() now checks whether the cached Koin instance's root scope is closed and resets the context when necessary, following the same recovery pattern already used by currentKoinScope().

This keeps locally provided Compose Koin contexts intact rather than replacing them with the global context.

Tests

Added regression coverage for:

• stopKoin() → startKoin() resolving the new Koin instance
• KoinIsolatedContext
• KoinApplicationPreview

The restart regression test fails on the previous implementation with ClosedScopeException and passes with this change.

Validation

Passed:

• ./gradlew :compose:koin-compose:jvmTest --rerun-tasks
• ./gradlew :compose:koin-compose:apiCheck
• ./gradlew :compose:koin-compose:compileTestKotlinWasmJs
• ./gradlew :compose:koin-compose:compileTestKotlinJs
• ./gradlew :compose:koin-compose:compileTestKotlinIosX64

The root ./gradlew apiCheck completed successfully for the library modules; :core:benchmark:jvmApiBuild has an unrelated failure under JDK 24 due to the binary compatibility validator not supporting bytecode level 68.

Fixes #2416