feat(npcs): drop binding; select NPCs on storyline export

Remove storyline/scene NPC binding and export chosen NPCs with relations/groups. Harden export modal so a missing npcs payload no longer blacks out the editor.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/main/index.ts

@@ -757,7 +757,7 @@ async function main() {
   });
   registerHandler(
     ipcChannels.project.upsertNpc,
-    async ({ npcId, name, description, filePath: pathFromDrop, groupId, binding }) => {
+    async ({ npcId, name, description, filePath: pathFromDrop, groupId }) => {
       let filePath = pathFromDrop;
       if (!filePath && !npcId) {
         const { canceled, filePaths } = await dialog.showOpenDialog({
@@ -781,7 +781,6 @@ async function main() {
           ...(typeof description === 'string' ? { description } : {}),
           ...(filePath ? { filePath } : {}),
           ...(groupId !== undefined ? { groupId } : {}),
-          ...(binding !== undefined ? { binding } : {}),
         },
         (p) => emitNpcUpsertProgress(p),
       );
@@ -793,12 +792,11 @@ async function main() {
   );
   registerHandler(
     ipcChannels.project.updateNpcFields,
-    async ({ npcId, name, description, groupId, binding }) => {
+    async ({ npcId, name, description, groupId }) => {
       const project = await projectStore.updateNpcFields(npcId, {
         ...(typeof name === 'string' ? { name } : {}),
         ...(typeof description === 'string' ? { description } : {}),
         ...(groupId !== undefined ? { groupId } : {}),
-        ...(binding !== undefined ? { binding } : {}),
       });
       emitSessionState();
       return { project };
@@ -1017,8 +1015,7 @@ async function main() {
     return { canceled: false as const, project };
   });
   registerHandler(ipcChannels.project.getProjectStorylines, async ({ projectId, labels }) => {
-    const storylines = await projectStore.getProjectStorylines(projectId, labels);
-    return { storylines };
+    return projectStore.getProjectStorylines(projectId, labels);
   });
   registerHandler(ipcChannels.project.peekImportZip, async ({ labels, targetHasMainStart }) => {
     const { canceled, filePaths } = await dialog.showOpenDialog({
@@ -1159,7 +1156,7 @@ async function main() {
       throw e;
     }
   });
-  registerHandler(ipcChannels.project.exportZip, async ({ projectId, storylineSelections, labels }) => {
+  registerHandler(ipcChannels.project.exportZip, async ({ projectId, storylineSelections, npcIds, labels }) => {
     const list = await projectStore.listProjects();
     const entry = list.find((p) => p.id === projectId);
     if (!entry) {
@@ -1183,6 +1180,7 @@ async function main() {
       await projectStore.exportStorylinesZipToPath(
         projectId,
         storylineSelections,
+        npcIds ?? [],
         dest,
         labels,
         (p) => {