Upgrade kmp and java apps to use 5.0.0-preview.3

[Ben Chatelain (phatblat)]

This PR updates the Java Server and Kotlin Multiplatform Quickstart apps to use Ditto 5.0.0-preview.3.

• https://docs.ditto.live/sdk/v5/release-notes/kotlin
• https://docs.ditto.live/sdk/v5/release-notes/java

Other Changes

• Renamed java-spring/ to java-server/
• Added java-server/java-spring-maven/ subproject for testing Maven compatibility

[Copilot]

Pull Request Overview

Upgrades Kotlin Multiplatform and Java applications to use Ditto SDK version 5.0.0-preview.3, updating the API implementation to match the new SDK interface.

• Updated Ditto SDK version from 5.0.0-preview.1 to 5.0.0-preview.3
• Migrated from DittoIdentity-based authentication to new authentication provider pattern
• Changed API method calls to use new naming conventions (e.g., registerObserver to observe, getString to asString)

Reviewed Changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
kotlin-multiplatform/composeApp/build.gradle.kts	Updated Ditto dependency versions to 5.0.0-preview.3
kotlin-multiplatform/composeApp/src/commonMain/kotlin/com/ditto/quickstart/ditto/DittoManager.kt	Refactored Ditto initialization to use new authentication pattern and updated API calls
kotlin-multiplatform/composeApp/src//kotlin/com/ditto/quickstart/ditto/DittoManager..kt	Updated platform-specific Ditto creation to use DittoFactory
kotlin-multiplatform/composeApp/src/commonMain/kotlin/com/ditto/quickstart/data/DittoCredentials.kt	Added new data class for Ditto credentials
kotlin-multiplatform/composeApp/src/commonMain/kotlin/com/ditto/quickstart/di/DittoModule.kt	Updated dependency injection to include credentials
kotlin-multiplatform/composeApp/src/commonMain/kotlin/com/ditto/quickstart/data/repository/DittoTaskRepository.kt	Updated API method call from registerObserver to observe
kotlin-multiplatform/composeApp/src/commonMain/kotlin/com/ditto/quickstart/ui/TaskAddEditScreen.kt	Minor UI layout adjustment
kotlin-multiplatform/README.md	Updated API reference link to preview.3 version
java-spring/src/main/java/com/ditto/example/spring/quickstart/service/DittoService.java	Migrated to new authentication pattern and updated transport configuration
java-spring/src/main/java/com/ditto/example/spring/quickstart/service/DittoTaskService.java	Updated API method calls to use new naming conventions
java-spring/build.gradle.kts	Updated Ditto dependency versions to 5.0.0-preview.3
java-spring/java-spring-maven/pom.xml	Added Maven configuration with preview.3 dependencies

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[Russell Wolf (russhwolf)]

What's the expected status of tests? The browserstack CI failure also happens for me locally, and I have similar failures in both the Android and iOS integration tests which are not being run in CI.

Otherwise, mostly nits here.

[Russell Wolf (russhwolf)]

Moving to approve after in-person convo that we haven't been maintaining those tests. We should probably update them at some point but I don't want to gatekeep this PR on that.