refactor speed, invulnerability; refactor move to use Vec2

types.h

@@ -11,6 +11,8 @@
 struct Player {
     Rectangle rect;
     uint8_t lives;
+    float speed;
+    float invulnerability_secs;
     double last_hit;
     float tear_speed;
     float tear_range;
@@ -22,7 +24,7 @@ struct Player {
 
     [[nodiscard]] bool is_invulnerable(double now) const noexcept;
 
-    void move(float delta_x, float delta_y);
+    void move(Vector2 delta);
 };
 
 enum Direction {