feat(kotlin-compose): design system + 33 components + gallery_kt + e2e android emulator + scaffolder fixes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cpp/functions/gamedev/camera_2d.h

@@ -0,0 +1,25 @@
+#pragma once
+
+// camera_2d — pure orthographic 2D camera (issue 0072b).
+// No state, no I/O. World <-> screen transforms + ortho view-projection matrix.
+
+#include "../core/math2d.h"
+
+namespace fn::cam {
+
+struct Camera2D {
+    fn::math2d::Vec2 pos = {0.0f, 0.0f};   // world position of camera center
+    float zoom = 1.0f;                      // 1 = no zoom; >1 zoom in
+    float rotation = 0.0f;                  // radians
+    int viewport_w = 1280;
+    int viewport_h = 720;
+};
+
+fn::math2d::Vec2 world_to_screen(const Camera2D& c, fn::math2d::Vec2 world);
+fn::math2d::Vec2 screen_to_world(const Camera2D& c, fn::math2d::Vec2 screen);
+fn::math2d::Rect visible_world_rect(const Camera2D& c);
+
+// Column-major 4x4 view-projection matrix (orthographic).
+void view_proj_matrix(const Camera2D& c, float out[16]);
+
+}  // namespace fn::cam