Installer authorization, language menu, and global satellite imagery

Beta 0.2.1.5 validates installation keys against the official SkyMission server for non-official domains, adds a flag-based language menu, provides theme-aware browser icons, standardizes the homepage message and administration cards, simplifies multilingual SEO, widens and aligns Mission Planner controls, automatically optimizes flight-line angles after area changes, adds global Esri World Imagery with visible attribution, and moves mission-file export to the bottom of Mission settings.