ea6e16358f
Implements a full level editor that runs inside the game engine as an alternative mode, accessible via --edit flag or E key during gameplay. The editor auto-discovers available tiles from the tileset texture and entities from a new central registry, so adding new game content automatically appears in the editor without any editor-specific changes. Editor features: tile painting (pencil/eraser/flood fill) across 3 layers, entity placement with drag-to-move, player spawn point tool, camera pan/zoom, grid overlay, .lvl save/load, map resize, and test play (P to play, ESC to return to editor). Supporting changes: - Entity registry centralizes spawn functions (replaces strcmp chain) - Mouse input + raw keyboard access added to input system - Camera zoom support for editor overview - Zoom-aware rendering in tilemap, renderer, and sprite systems - Powerup and drone sprites/animations wired up (were defined but unused) - Bitmap font renderer for editor UI (4x6 pixel glyphs, no dependencies)