Display Fixes & Linux Support — Mega Roids Steam update #394881

Patch Notes 🖥️ Display Improvements Widescreen & Non-4:3 Display Support — The game now correctly letterboxes or pillarboxes on displays that aren't 4:3, preserving the intended aspect ratio instead of stretching. Viewport rect is now cached and only recalculated on resize, improving rendering performance. Fixed an issue where querying display pixel size immediately after entering fullscreen could return incorrect dimensions — the game now pumps SDL events first to ensure accurate output. Fixed an edge case where the logical presentation could cause stretching artifacts by switching to SDL_SetRenderLogicalPresentation. 🐧 Linux Support Linux/Debian builds are now officially supported! The game can be compiled and run on Linux via CMake. Bundled GLM headers are now used, removing a broken external dependency fetch. A Linux README has been added with build instructions. 🔧 Bug Fixes & Code Q...