Add distance measurement persistence to maps

[1Blademaster]

No description provided.

[Copilot]

Pull request overview

This PR moves distance measurement state out of component-local state and into Redux so measurements persist on both the dashboard map and missions map while navigating/closing context menus, and adds UI support for deleting a saved measurement via context menu.

Changes:

• Add distanceMeasurements (draft start + saved items) to both missionSlice and dashboardSlice, with actions/selectors to manage them.
• Update the dashboard and missions map components to use Redux-backed distance measurement state and to allow deleting a saved measurement.
• Refactor DistanceMeasurementMarkers to render persistent start/end pins, a connecting line, and a midpoint label showing the measured distance.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
gcs/src/redux/slices/missionSlice.js	Adds Redux state/actions/selectors for mission-map distance measurement persistence.
gcs/src/redux/slices/dashboardSlice.js	Adds Redux state/actions/selectors for dashboard-map distance measurement persistence.
gcs/src/components/missions/missionsMap.jsx	Switches distance measurement from local state to Redux and adds “Delete distance measurement” context action.
gcs/src/components/mapComponents/distanceMeasurement.jsx	Reworks rendering to show persistent measurement pins/lines and a midpoint distance label.
gcs/src/components/dashboard/map.jsx	Switches distance measurement from local state to Redux and adds “Delete distance measurement” context action.

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