Remove per-item cutscene authoring macros

Every CUTSCENE_XXX(...) shorthand (CUTSCENE_WAIT, CUTSCENE_TEXT,
CUTSCENE_ENTITY_WALK_TO, etc.) existed to build a cutsceneitem_t literal
in C; real cutscenes are now authored exclusively as .jsonc files, and
the only other users were test fixtures. Deletes all ~55 of these
macros (and the shared CUTSCENE_ITEM(...) helper they built on) along
with their doc comments, leaving each item's struct/enum/Start/Update/
Load declarations untouched.

test_battle.c, test_cutscenecontrol.c, test_cutscenemaparea.c,
test_cutscenesystem.c and test_entityinteract.c now build their
cutsceneitem_t fixtures as plain struct literals instead.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/dusk/rpg/cutscene/item/audio/cutsceneaudioresume.h

@@ -9,14 +9,6 @@
 #include "audio/mixer/audiomixerchannel.h"
 #include "rpg/cutscene/item/cutsceneitembase.h"
 
-/**
- * Resumes CHANNEL immediately.
- *
- * @param CHANNEL audiomixerchannel_t to resume.
- */
-#define CUTSCENE_AUDIO_RESUME(CHANNEL) \
-  CUTSCENE_ITEM(CUTSCENE_ITEM_TYPE_AUDIO_RESUME, audioResumeChannel, CHANNEL)
-
 /**
  * Starts an audio resume step (resumes the channel immediately).
  *