v0.3.0-beta.3

Added

• Combined groups: sensor.*_recently_offline — aggregates recently offline entities from all member groups into a single sensor; uses each source group's own recovery window
• Combined groups: sensor.*_recently_recovered — aggregates recently recovered entities from all member groups; same per-group window logic
• Combined groups: battery_powered count added to sensor.*_combined_summary attributes (top-level total and per-group breakdown in the groups attribute)