feat(weather): allow manual latitude/longitude input

[saulob]

Description

This PR improves the Weather plugin by allowing users to manually input latitude and longitude, instead of relying only on the map picker.

This change was inspired by the feature request discussed here: #564

What was done

• Allow direct input of latitude and longitude
• Remove readonly restriction from coordinate fields
• Sync manually entered coordinates when opening the map modal (validated with Number.isFinite)
• Reinitialize map view and marker when reopening with updated coordinates
• Adjust zoom level dynamically based on coordinate presence. Prevents incorrect zoom when users add or remove coordinates after page load. Ensures the map view always matches the current state of the inputs

Why this matters

• Fixes cases where Select Location may not work or appear blank
• Improves usability by allowing quick manual input
• Provides a fallback option without breaking existing behavior

Additional Notes

• No breaking changes
• Existing map selection flow remains unchanged
• Manual input supports validation and proper error handling for invalid values
• Invalid inputs (non-numeric values) are safely handled and return clear error messages without breaking the flow

Screenshots

• Map picker automatically synced with manually entered coordinates
• Successful update after entering coordinates directly in the input fields

[Copilot]

Pull request overview

This PR updates the Weather plugin settings UI to support manually entering latitude/longitude while keeping the existing Leaflet map picker workflow.

Changes:

• Makes latitude/longitude inputs editable (removes readonly).
• Re-reads and syncs lat/long from inputs when opening the map modal, and refreshes the map view/marker on reopen.
• Adjusts how saved settings populate the coordinate fields.

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[saulob]

All Copilot review comments addressed