fix: resolve 9 P0+P1 review findings (bills decorators, campus isolation bypass, ding raw crash, batch import counter, SSE multi-tab, interval leak, dept permissions, cycle prevention, tree depth)

apps/server/src/common/campus-scope.ts

@@ -44,7 +44,13 @@ export class CampusScope {
     }
 
     const ids = await this.getEffectiveScopeIds();
-    if (ids.length === 0) return where;
+    if (ids.length === 0) {
+      // Non-super-admin with no scoping → match nothing, never leak unfiltered data
+      if (!this.isSuperAdmin) {
+        return { ...where, departmentId: In([]) } as unknown as T;
+      }
+      return where;
+    }
 
     return { ...where, departmentId: In(ids) } as unknown as T;
   }