feat(ui): add zone order and measurement labels

[godiak]

Adds UI labels for zone order and configurable map measurements.

Changes:

• Adds a "congatudo.zoneMeasurement" configuration section.
• Adds "cmPerMapUnit" to scale manual zone dimension labels.
• Adds "segmentAreaMultiplier" to optionally scale displayed room/segment area labels.
• Adds a read-only config endpoint for the frontend.
• Uses the configured values only for displayed labels.
• Shows compact measurement labels only when a zone is selected.
• Adds visible order numbers to selected zones.
• Adds a Manual/Auto zone order mode in the zone cleaning UI.
• Manual mode keeps the visible/manual zone order.
• Auto mode computes an approximate economical order, shows that order on the selected zones, and sends the zones array already ordered.

Payload behavior:

• The backend API is unchanged.
• The UI still sends the existing "zones" array and "iterations" field.
• This PR only changes the order of the "zones" array before sending it.
• Measurement labels do not affect robot payloads.

This does not change map coordinates, firmware behavior, "cleanAreas", "cleanRooms", segment cleaning, zone cleaning backend behavior, or Cecotec room custom ordering support.

Example local configuration:

{
"congatudo": {
"zoneMeasurement": {
"cmPerMapUnit": 5.15,
"segmentAreaMultiplier": 250
}
}
}

Defaults keep existing behavior unless the user configures a custom scale.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.7% Duplication on New Code

See analysis details on SonarQube Cloud