[WieszczY85]

Motivation

• Provide a minimal, packet-independent networking slice that can perform offline-mode login and basic play handling for Minecraft Java protocol 47 so the app can connect to legacy servers or proxies.
• Introduce an observable session lifecycle and safe domain error mapping so UI can react to connection state changes without depending on packet types.
• Surface a quick-connect UI path for direct TCP connections to a server endpoint using a username so the prototype can demonstrate end-to-end chat/command flow.

Description

• Add a new packet codec and legacy protocol adapter: protocol/legacy/ProtocolCodec.kt and LegacyOfflineMinecraftConnection implementing MinecraftConnection with handshake, login, compression negotiation, keep-alive replies, position acknowledgement, chat and command sending, and typed MinecraftConnectionException results.
• Introduce a session domain contract and models in domain/session including SessionManager, SessionManagerFactory, SessionSnapshot, ConnectionState, SessionError and SessionEvent.
• Implement DefaultSessionManager (and DefaultSessionManagerFactory) which serializes lifecycle operations, publishes StateFlow/SharedFlow, and maps MinecraftConnectionException to SessionError values.
• Wire UI to the new session API: CraftConnectApp now accepts a SessionManagerFactory, ServersScreen includes an offline quick-connect dialog and accepts a ConnectionState, and ChatScreen accepts an onSend callback hooked to SessionManager send methods; DemoRepository and resources/README/ARCHITECTURE updates document the change.
• Update build configuration to add coroutines and test dependencies in gradle/libs.versions.toml and app/build.gradle.kts.

Testing

• Added unit tests DefaultSessionManagerTest, ProtocolCodecTest and an integration-style local-socket test LegacyOfflineMinecraftConnectionTest under app/src/test and executed them via the Gradle test task (e.g. ./gradlew :app:testDebugUnitTest).
• All added tests passed successfully.

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Codex Task