Localized administration and resilient geometry sync

Recovers mapping corners from the visible draggable markers before route regeneration and save
Falls back safely to current state, last valid state, or the synchronized hidden polygon transport
Never restores a polygon after the user explicitly clears the geometry
Adds the selected geometry source to every save diagnosis
Lets a platform administrator delete another user only after explicit confirmation
Prevents administrator self-deletion and deletion of the last active platform administrator
Uses existing foreign-key policies to remove directly associated memberships, personal drone selections, and mission data
Localizes administration in English, German, French, and Luxembourgish while leaving user data, domains, filenames, and checksums unchanged
Universal install/update package supports Betas 0.15 through 0.38