feat(npcs): add campaign NPCs with relation graph and session overlay

Add a dedicated NPC editor window, directed relations, control/presentation avatar overlay, and ru/en help for the new section.

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

app/main/project/assetPrune.ts

@@ -15,6 +15,7 @@ export function collectReferencedAssetIds(p: Project): Set<AssetId> {
   }
   for (const au of p.campaignAudios) refs.add(au.assetId);
   for (const m of p.materials ?? []) refs.add(m.assetId);
+  for (const n of p.npcs ?? []) refs.add(n.avatarAssetId);
   return refs;
 }