修复验收：修正最终验收证据问题

scripts/qa/teacher_student_browser_e2e_runner.py

@@ -53,8 +53,9 @@ def backend_login(username, password):
 
 class Round3BRunner:
     def __init__(self):
-        self.env = load_qa_env()
-        self.qa_password = self.env.get('QA_ADMIN_PASSWORD', 'admin123')
+        self.qa_password = self.env.get('QA_ADMIN_PASSWORD')
+        if not self.qa_password:
+            raise RuntimeError("QA_ADMIN_PASSWORD is required and must be configured in environment or ~/.railwaysystem-qa.env")
         self.stats = {
             "http_500_count": 0,
             "blocking_console_error_count": 0,
@@ -524,8 +525,11 @@ class Round3BRunner:
         }""")
         for k, v in storage_data['localStorage'].items():
             val = str(v).lower()
-            assert 'admin123' not in val, f"Plaintext password leaked in localStorage key {k}"
-            assert 'fcd1cf253af502ee' not in val, f"AppSecret leaked in localStorage key {k}"
+            if self.qa_password:
+                assert self.qa_password.lower() not in val, f"Plaintext password leaked in localStorage key {k}"
+            dms_secret = self.env.get('DMS_APP_SECRET')
+            if dms_secret:
+                assert dms_secret.lower() not in val, f"AppSecret leaked in localStorage key {k}"
         self.evidence["SECURITY_RUNTIME"] = "PASS"
         self.log("Security Storage Audit: 0 Plaintext Secrets Found.")