Update Kotlin and core extension

[simolus3]

Release notes for the core extension: https://github.com/powersync-ja/powersync-sqlite-core/releases/tag/v0.4.6

This also prepares the adoption of a Kotlin SDK update to fix XCode 26 compatibility (powersync-ja/powersync-kotlin#260).
It also adds the getCrudTransactions API we've recently added to our other SDKs.

[simolus3]

@stevensJourney I'm not sure what to do about the compiler errors with XCode 26. It complains about the override func __uploadData(database _: KotlinPowerSyncDatabase) async throws method on PowerSyncBackendConnectorAdapter("Non-Sendable parameter type 'any PowerSyncDatabase' cannot be sent from caller of superclass instance method '__uploadData(database:)' into nonisolated override").

Since we can't mark any PowerSyncDatabase (the Kotlin one) as sendable because it's an interface, I'm not sure we can fix this from Swift alone.

[stevensJourney]

@stevensJourney I'm not sure what to do about the compiler errors with XCode 26. It complains about the override func __uploadData(database _: KotlinPowerSyncDatabase) async throws method on PowerSyncBackendConnectorAdapter("Non-Sendable parameter type 'any PowerSyncDatabase' cannot be sent from caller of superclass instance method '__uploadData(database:)' into nonisolated override").

Since we can't mark any PowerSyncDatabase (the Kotlin one) as sendable because it's an interface, I'm not sure we can fix this from Swift alone.

We don't actually use the KotlinPowerSyncDatabase in our override. Since we want to wrap and provide a Swift protocol for uploads. We could create a small helper on the Kotlin side which implements uploadData with another overrideable method like performUpload which does not require a parameter. e.g.

public class SwiftConnector : PowerSyncBackendConnector() {
    override suspend fun fetchCredentials(): PowerSyncCredentials? {
    }

    // Have Swift SDK overide this
    public suspend fun performUpload() {
    }

    override suspend fun uploadData(database: PowerSyncDatabase) {
        performUpload()
    }
}

[simolus3]

Sounds good, I'll open a Kotlin PR for this 👍