Added

• New optional TeamsChestService interface for team chest access: getChestIds(teamId), getContents(...), setContents(...), addItem(...), and removeItem(...).
• New TeamsAPI chest facade methods: getChestService(), isChestAvailable(), registerChestProvider(plugin, service), registerChestProvider(plugin, service, priority), and unregisterChestProvider(service).
• New API tests: TeamsAPIChestTest for chest provider registration, null-safety, priority registration, and service independence from core TeamsService.
• New docs pages: provider-chests (provider implementation/registration guidance) and consumer-chests (consumer usage patterns and fallback guards).

Changed

• TeamsAPI version bumped from 2.2.0 to 2.3.0 (non-breaking minor release).
• TeamsAPI.API_VERSION bumped to 2.3.0.
• README, API docs, provider/consumer guides, server guide, and public listings updated to include the optional chest capability and 2.3.0 dependency examples.