Fix missing sdl3game.pc for pkg-config, change sprite speed and character movement values to long int expressed in nanoseconds for better compatibility with SDL_Time and locking against game clock, still expressed as milliseconds in json

include/sdl3game/actor.h

@@ -68,7 +68,7 @@ typedef struct actor {
   bool movement_controls_face;
   void *actorData;
   bool visible;
-  int logictimer;
+  SDL_Time logictimer;
   float x;
   float y;
   struct actor *children[ACTOR_MAX_CHILDREN];