v0.3.15 - Eletta maintenance binary sensors

Adds maintenance binary sensors for ECAM models (Eletta Explore, DL-striker-cb), cherry-picked from @TischenkoArseny's work in PR #9 / issue #7.

Added

• 4 maintenance binary sensors (ECAM only): Water tank empty, Waste container full, Decalcification needed, Filter change needed - decoded from the d302_monitor_machine MonitorV2 switches/alarms bitfields (DlghIoT layout).
• MonitorV2 parsing of the 16-bit switches and 32-bit alarms bitfields.
• Machine Status sensor now exposes switches/alarms as hex diagnostic attributes (ECAM only).
• Entity-name translations (en/fr/cs) for the new binary sensors.
• Unit tests for the new bitfield parsing.

Notes

• PrimaDonna Soul (DL-millcore) unchanged: every new entity/attribute is gated on uses_cloud_session, so the Soul gets no new entities and behaves identically.
• The counter / Last-Connected improvements proposed in PR #9 are not included here - they were already shipped in v0.3.14 (issue #7, @kasiom), and this release builds on that.

Thanks to @TischenkoArseny for the contribution. 🙏