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/shared/ipc/contracts.ts

@@ -12,7 +12,6 @@ import type {
   NpcId,
   NpcRelationId,
   NpcGroupId,
-  NpcBinding,
   NpcsOverlayEvent,
   NpcsOverlayState,
   Project,
@@ -369,7 +368,6 @@ export type IpcInvokeMap = {
       description?: string;
       filePath?: string;
       groupId?: NpcGroupId | null;
-      binding?: NpcBinding;
     };
     res: { project: Project };
   };
@@ -379,7 +377,6 @@ export type IpcInvokeMap = {
       name?: string;
       description?: string;
       groupId?: NpcGroupId | null;
-      binding?: NpcBinding;
     };
     res: { project: Project };
   };
@@ -493,7 +490,10 @@ export type IpcInvokeMap = {
   };
   [ipcChannels.project.getProjectStorylines]: {
     req: { projectId: ProjectId; labels: StorylineLabels };
-    res: { storylines: StorylineListItem[] };
+    res: {
+      storylines: StorylineListItem[];
+      npcs: { id: string; name: string }[];
+    };
   };
   [ipcChannels.project.peekImportZip]: {
     req: { labels: StorylineLabels; targetHasMainStart: boolean };
@@ -560,7 +560,12 @@ export type IpcInvokeMap = {
     res: { project: Project };
   };
   [ipcChannels.project.exportZip]: {
-    req: { projectId: ProjectId; storylineSelections: StorylineSelection[]; labels: StorylineLabels };
+    req: {
+      projectId: ProjectId;
+      storylineSelections: StorylineSelection[];
+      npcIds: string[];
+      labels: StorylineLabels;
+    };
     res: { canceled: true } | { canceled: false };
   };
   [ipcChannels.project.deleteProject]: {