Configurator: draw the moving-map zoom rail in the twin and expose zoom_rail

[billmallard]

Summary

billmallard/pyEfis#205 adds a one-finger zoom rail to the moving map. It is a vertical rail under the status chip, with a thumb at the current range rung and +/- caps at the ends.

Two things are needed here:

• The twin must draw it. The configurator's moving-map twin in configurator/public/editor.html has to reproduce what pyEfis renders (the fidelity rule).
• The editor must expose the new zoom_rail option.

Scope

• Render the rail in the moving-map twin. Use the same position, proportions and style as the pyEfis widget, with the thumb at the configured range_nm rung. Match it against an offscreen render of the real widget, not against a description.
• Check the option end to end. It arrives through the schema.json exported from the pyEfis registry. Confirm it appears in the inspector and round-trips into the generated config.
• No change to how the device pulls config.

Acceptance

• Screenshot comparison. The twin beside the pyEfis offscreen render at 10 NM, at the same map size.
• Toggle works. zoom_rail turns the rail on and off in the preview and in the saved config.
• Lockstep. Lands together with Map: one-finger zoom rail - on-screen range control under the status chip pyEfis#205, on dev in both repos.

Related

billmallard/pyEfis#205, billmallard/pyEfis#136.