Add order-based party roster, back-navigation in battle selection, fix win-state cutscene leak

- Battle selection menu can now go back a fighter to re-decide their move,
  and battle win/loss no longer leaks the round's remaining queued move
  cutscenes into the ending state (cutsceneSystemDiscardQueued).
- Party roster is now driven by party.jsonc: every defined member always
  exists (partyInit), while party->order alone determines who's currently
  active - partyAddMember/partyRemoveMember (and their cutscene items) now
  activate/deactivate an existing roster member by index instead of
  creating/destroying one, with removal compacting order to stay packed.
- New PARTY_ADD_MEMBER/PARTY_REMOVE_MEMBER/PARTY_HEAL_MEMBER/PARTY_HEAL_ALL
  cutscene items.
- saveSlotInit/partyInit now return errorret_t and take their target
  struct directly (saveslot_t*/party_t*) instead of implicitly operating
  on SAVE.slot; saveSlotReadJSON resets through saveSlotInit rather than
  duplicating the reset logic.
- Test coverage: stub the JSON asset loader in save test fixtures so
  partyInit's real party.jsonc load runs against an in-memory doc instead
  of hanging with no asset system initialized.

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

test/save/savetestfixture.c

@@ -10,6 +10,9 @@
 
 #include "savetestfixture.h"
 #include "assert/assert.h"
+#include "asset/asset.h"
+#include "asset/loader/assetloader.h"
+#include "asset/loader/assetentry.h"
 #include "util/memory.h"
 #include "util/string.h"
 #include <ftw.h>
@@ -22,6 +25,51 @@ static char_t SAVE_TEST_FIXTURE_HOME[PATH_MAX];
 static char_t SAVE_TEST_FIXTURE_REAL_HOME[PATH_MAX];
 static bool_t SAVE_TEST_FIXTURE_HAD_REAL_HOME;
 
+static const char_t *SAVE_TEST_FIXTURE_PARTY_JSON =
+  "{\"members\":[{"
+    "\"attack\":10,\"defense\":5,\"magic\":0,\"speed\":10,\"luck\":0,"
+    "\"healthMax\":30,\"mpMax\":10"
+  "}]}";
+
+static yyjson_doc *SAVE_TEST_FIXTURE_PARTY_DOC = NULL;
+
+errorret_t saveTestFixturePartyJsonLoadSyncStub(assetloading_t *loading) {
+  loading->entry->data.json = SAVE_TEST_FIXTURE_PARTY_DOC;
+  loading->entry->state = ASSET_ENTRY_STATE_LOADED;
+  errorOk();
+}
+
+errorret_t saveTestFixturePartyJsonDisposeStub(assetentry_t *entry) {
+  errorOk();
+}
+
+void saveTestFixtureStubPartyAsset(void) {
+  memoryZero(&ASSET, sizeof(ASSET));
+  for(size_t i = 0; i < ASSET_LOADING_COUNT_MAX; i++) {
+    threadMutexInit(&ASSET.loading[i].mutex);
+  }
+
+  if(SAVE_TEST_FIXTURE_PARTY_DOC == NULL) {
+    SAVE_TEST_FIXTURE_PARTY_DOC = yyjson_read(
+      SAVE_TEST_FIXTURE_PARTY_JSON, strlen(SAVE_TEST_FIXTURE_PARTY_JSON), 0
+    );
+    assertNotNull(
+      SAVE_TEST_FIXTURE_PARTY_DOC, "Failed to parse party JSON fixture"
+    );
+  }
+
+  ASSET_LOADER_CALLBACKS[ASSET_LOADER_TYPE_JSON].loadSync =
+    saveTestFixturePartyJsonLoadSyncStub;
+  ASSET_LOADER_CALLBACKS[ASSET_LOADER_TYPE_JSON].dispose =
+    saveTestFixturePartyJsonDisposeStub;
+}
+
+void saveTestFixtureUnstubPartyAsset(void) {
+  if(SAVE_TEST_FIXTURE_PARTY_DOC == NULL) return;
+  yyjson_doc_free(SAVE_TEST_FIXTURE_PARTY_DOC);
+  SAVE_TEST_FIXTURE_PARTY_DOC = NULL;
+}
+
 static int_t saveTestFixtureRemoveEntry(
   const char *path,
   const struct stat *statBuffer,
@@ -49,6 +97,8 @@ int saveTestFixtureSetup(void **state) {
 
   assertTrue(setenv("HOME", SAVE_TEST_FIXTURE_HOME, 1) == 0, "setenv failed");
 
+  saveTestFixtureStubPartyAsset();
+
   errorret_t ret = saveInit();
   assertTrue(errorIsOk(ret), "saveInit failed in test fixture");
 
@@ -56,6 +106,8 @@ int saveTestFixtureSetup(void **state) {
 }
 
 int saveTestFixtureTeardown(void **state) {
+  saveTestFixtureUnstubPartyAsset();
+
   nftw(
     SAVE_TEST_FIXTURE_HOME, saveTestFixtureRemoveEntry, 16,
     FTW_DEPTH | FTW_PHYS