fix: expose service response in HA Actions UI for get_smart_meter_readings and export_smart_meter_csv - #87

Both service handlers returned a dict but were registered without supports_response, so Home Assistant silently discarded the return value — the Actions UI showed nothing, only the fired event carried the data.

Changes

• __init__.py — import SupportsResponse from homeassistant.core; register both response-returning services with supports_response=SupportsResponse.ONLY:

hass.services.async_register(
    DOMAIN,
    SERVICE_GET_SMART_METER_READINGS,
    handle_get_smart_meter_readings,
    supports_response=SupportsResponse.ONLY,
)
hass.services.async_register(
    DOMAIN,
    SERVICE_EXPORT_SMART_METER_CSV,
    handle_export_smart_meter_csv,
    supports_response=SupportsResponse.ONLY,
)

• services.yaml — updated export_smart_meter_csv description to document the service response (matching the existing wording on get_smart_meter_readings).
• manifest.json — version bump 0.0.95 → 0.0.96.
• RELEASE_NOTES.md — added v0.0.96 entry.

Existing fired events (octopus_germany_smart_meter_readings_result, octopus_germany_csv_export_result) and all validation/error paths are unchanged.