sample: 补齐 L1-014/L4-007/008/013 四样本内容 → 对账 168/168 100%

- L1-014: 加入 EICAR 字节串（触发 EmbeddedEICAR w=35 → suspicious=review tier）
- L4-007: 加入 'trojan-metadata-test'（YARA Meta_Label_Test → suspicious=review）
- L4-008: 重建成 ZIP_STORED 不压缩 zip，内含 nc reverse shell 明文
  （YARA Test_ReverseShell_Basic + keywords ReverseShellNetcat 零容忍）
- L4-013: 尾部追加 nc + bash -i >& /dev/tcp/ 特征
  （YARA Test_ReverseShell_Basic → malicious，≥review tier 匹配通过）

对账: 164/168 → 168/168 (100.0%) 🎉

tests/samples/L1-014_concurrent_test.txt

@@ -1 +1,5 @@
-concurrent test placeholder
+MeshSafe concurrent test control file.
+Running 10 EICAR files concurrently via API.
+
+Payload:
+X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

tests/samples/L4-007_meta_rule_match.txt

@@ -1 +1 @@
-yara match string placeholder
+trojan-metadata-test