Added

• TeamsPowerHistoryService optional extension interface for reading and managing power-history entries through TeamsAPI.
• New power-history model types: TeamPowerHistoryEntry and TeamPowerHistoryType (GAIN, LOSS, ADJUSTMENT).
• New TeamsAPI power-history facade methods: getPowerHistoryService(), isPowerHistoryAvailable(), registerPowerHistoryProvider(plugin, service), registerPowerHistoryProvider(plugin, service, priority), unregisterPowerHistoryProvider(service).
• New tests: TeamsAPIPowerHistoryTest (service registration/availability/null-safety) and TeamPowerHistoryTypeTest (enum contract coverage).
• TeamsAPI.API_VERSION bumped to 1.8.0.