Include actor.h from controller.h so the header compiles on its own

controller.h declares three handler pointers taking an akgl_Actor * and
included nothing that declares that type, so any translation unit reaching
for it before akgl/actor.h failed with "unknown type name 'akgl_Actor'".
src/controller.c never noticed because it includes akgl/game.h first, and
tests/controller.c carried a comment explaining the workaround.

Included rather than forward-declared: akgl_Actor is a typedef of a named
struct and repeating a typedef is C11, not C99. It closes no cycle --
actor.h reaches only types.h and character.h.

tests/headers.c is a whole suite for one #include on purpose. A second
#include after the first proves nothing about the second, because by then
the first has dragged its dependencies in; covering another header means
another file shaped like this one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

include/akgl/controller.h

@@ -30,6 +30,12 @@
 #include <SDL3/SDL.h>
 #include <akerror.h>
 #include "types.h"
+// The binding handlers below take an akgl_Actor *, so this header cannot be
+// included before akgl/actor.h without one. akgl_Actor is a typedef of a named
+// struct, and repeating a typedef is not C99, so it is included rather than
+// forward-declared. actor.h reaches only types.h and character.h, so this does
+// not close a cycle.
+#include <akgl/actor.h>
 
 /** @brief How many control maps exist -- effectively the local player limit. */
 #define AKGL_MAX_CONTROL_MAPS 8