Persist and resume in-progress cutscene via save slot; add species stub

Save slots now track the currently-active cutscene file (defaulting to a
new placeholder new_game.jsonc intro) so loading a save resumes it;
cutsceneSystemStartCutsceneWith persists this on every cutscene start, and
a cutsceneSystemLoad ordering bug (loadedFile stamped after starting) is
fixed so the persisted path is always correct. Also adds a
battlefighterspecies_t/battlespeciesid_t stub for upcoming species data.

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

assets/cutscenes/new_game.jsonc

@@ -0,0 +1,11 @@
+{
+  // Placeholder for the new-game intro flow - just shows a modal for now.
+  "items": [
+    {
+      "type": "MODAL",
+      "title": "New Game",
+      "message": "This is a placeholder for the new game intro.",
+      "blocking": true
+    }
+  ]
+}

assets/party.jsonc

@@ -1,16 +1,22 @@
 {
-  // Starting party roster, loaded by partyInit into a fresh save slot.
-  // Each key is a stable identifier cutscene content can reference
-  // directly (see PARTY_ADD_MEMBER/PARTY_REMOVE_MEMBER/PARTY_HEAL_MEMBER's
-  // "key" field) instead of a fragile positional index.
   "members": {
     "hero": {
-      "attack": 10, "defense": 5, "magic": 0, "speed": 10, "luck": 0,
-      "healthMax": 30, "mpMax": 10
+      "attack": 10,
+      "defense": 5,
+      "magic": 0,
+      "speed": 10,
+      "luck": 0,
+      "healthMax": 30,
+      "mpMax": 10
     },
     "companion": {
-      "attack": 8, "defense": 6, "magic": 4, "speed": 8, "luck": 1,
-      "healthMax": 25, "mpMax": 15
+      "attack": 8,
+      "defense": 6,
+      "magic": 4,
+      "speed": 8,
+      "luck": 1,
+      "healthMax": 25,
+      "mpMax": 15
     }
   }
 }