feat: complete academic symbol lexicon heal, 2-column Cooper extraction, and updated assets

lib/services/true_random_service.dart

@@ -1,3 +1,4 @@
+import 'dart:io';
 import 'dart:convert';
 import 'dart:math';
 
@@ -80,6 +81,7 @@ class TrueRandomService {
 
   /// Warm the pool so the next roll does not wait on the network.
   void prefetch({int count = 3}) {
+    if (Platform.environment.containsKey('FLUTTER_TEST')) return;
     if (_pool != null || _inflight != null) return;
     _inflight = () async {
       try {