Implements GET /api/v1/weather/nearby endpoint with comprehensive parameter
validation and error handling. The controller validates required parameters
(lat, lon, radius) and optional parameters (hours, limit) with appropriate
range checking. Integrates with PreparedQueries for efficient database access
and WeatherJSON for response serialization.
Key features:
- Required params: lat (-90 to 90), lon (-180 to 180), radius (0-1000 miles)
- Optional params: hours (1-168, default 6), limit (1-100, default 50)
- Proper error responses via FallbackController (400 for bad requests, 422 for validation)
- Full test coverage (16 tests) including edge cases and error scenarios
Also updates FallbackController to handle {:error, status, message} tuples
and fixes WeatherJSON to support both field name formats (lat/lon and latitude/longitude)
for compatibility with existing tests and actual query results.
