v0.125.0

Added

• [MET Norway Frost] Add new provider metno/frost for the Norwegian Meteorological Institute's Frost API. Supports 10-minute, hourly, 6-hour, daily, monthly and annual resolutions with ~2200 stations across Norway. Authentication via free API key (WD_AUTH__METNO_FROST env var). Historical synoptic 6-hourly data is retrieved via an availableTimeSeries fallback that resolves the time-series-specific query parameters required by the Frost API.
• [Settings] Load .env files automatically via env_file=".env" and support nested env vars via env_nested_delimiter="__" (e.g. WD_TS_UNIT_TARGETS__temperature=degree_fahrenheit).
• [Metadata] Add auth: bool = False field to MetadataModel so providers requiring an API key can declare it. Defaults to False for all existing providers.
• [API] Add is_configured() -> bool and is_valid() -> bool classmethods to TimeseriesRequest. is_configured checks whether credentials are present (cheap, offline); is_valid probes the API to confirm they actually work (should be cached by the implementation). Both default to True for providers that need no auth.
• [REST API] GET /api/coverage (no parameters) now returns {provider: {network: {auth: bool, configured: bool, valid: bool}}} instead of {provider: [network]}, exposing per-network auth status to API consumers.
• [REST API] Add GET /api/auth?provider=&network= endpoint that returns {provider, network, auth, configured, valid} for a specific provider/network, allowing clients to re-check credential validity without fetching all coverage. valid is always false when configured is false (probe cannot run without credentials).

Full Changelog: v0.124.0...v0.125.0