fix: tighten sharing and shadcn composition

src/modules/_core/share-authorization.ts

@@ -0,0 +1,16 @@
+import type { EntityTypeRegistration, ShareContext } from "./module";
+
+export async function ensureEntityShareAuthorized(
+  registration: EntityTypeRegistration,
+  entityId: string,
+  ctx: ShareContext,
+): Promise<void> {
+  if (!registration.canShareEntity) {
+    throw new Error(`Entity type "${registration.type}" does not support share authorization`);
+  }
+
+  const allowed = await registration.canShareEntity(entityId, ctx);
+  if (!allowed) {
+    throw new Error("You are not allowed to share this entity");
+  }
+}