v0.3.14 - Eletta Explore counters, JSON counter parsing, i18n

Integrates the field-tested contribution from @kasiom (#7) after a security audit (no new hosts, no dynamic code/network) and a rework for testability.

Added

• Eletta Explore (450.65.G) counter sensors mapped from the real Ayla datapoint dump (#7): iced beverages, cold brew, hot/cold mug drinks, per-recipe totals, total descales (d552), total water (d553), filters used (d554), filtered-water qty (d555). Each sensor is created only when its datapoint is present, so the PrimaDonna Soul is unaffected.
• Czech localisation (cs.json) and full French entity names.

Fixed

• JSON-aggregated counters (#7): newer models publish some counters (e.g. d735_iced_bev, d738_cold_brew_bev) as a JSON blob; the sensor now sums the integer sub-values for the state and exposes the breakdown as attributes. Plain-integer counters (Soul) are unchanged.
• Last Connected raw base64 (#7): now uses the property data_updated_at timestamp with device_class: timestamp.

Changed

• Entity names migrated to Home Assistant translation keys (sensors + buttons), HA best practice. Entity ids are unchanged, so existing dashboards/automations keep working.

Notes

• Issue #10 (counters frozen on the Soul) is a separate cloud-sync limitation, not addressed here.

Credit: @kasiom (#7). 84 unit tests pass.