Widgets: weather and location tied to the profile's coordinates #69

Part of #67 — Widgets, location and weather

GET /api/weather and GET /api/location, driven by the account's latitude/longitude
(set in the Settings epic) or the device's current location.

• Must degrade cleanly with no location permission and no stored coordinates.

Tests: parse; no-location fallback.

Filed from the parity review of feature/parity-wip @ 14d7795 against interlinedlist.com (OpenAPI /api/openapi.json, 233 paths) and the public help centre.