Fixes#62
Fixes rainfall unit inconsistency
Updates daily rain sensor to use consistent measurement units and corrects device class and suggested unit.
Fixes#62
Adds database path constant and data migration function
Defines DATABASE_PATH constant for database file location
Introduces migrate_data function to update unit of measurement in long statistics.
Adds sensor migration feature
Introduces a migration step for sensor statistics
Updates schema and translations to support migration
Fixes data migration from mm/d to mm
Includes new sensor connection status constants and mappings
Updates WeatherSensor to handle null data values
Switches temperature unit to Celsius for WSLink sensors
Refines heat and chill index calculations with unit conversions
schizza