fix(unityfs): 加固基础容器解析校验

补充 UnityFS 总大小、block/directory 计数、目录路径、重复项和边界校验，覆盖 LZMA 数据块与损坏输入回归。新增隔离真实 UnityPy bundle 测试入口，并用 /tmp 中的 char_118_yuki.ab 完成实际回归。复杂对象解析与发布级重打包继续保留在 G-005 后续范围。

Fixes #3

crates/bat-assetbundle/tests/real_unityfs_reference.rs

@@ -0,0 +1,24 @@
+use bat_assetbundle::UnityFsParser;
+use std::path::PathBuf;
+
+#[test]
+#[ignore = "requires BAT_REAL_UNITYFS_BUNDLE pointing at an isolated real UnityFS bundle"]
+fn parses_isolated_real_unityfs_bundle() {
+    let path = PathBuf::from(
+        std::env::var("BAT_REAL_UNITYFS_BUNDLE").expect("BAT_REAL_UNITYFS_BUNDLE must be set"),
+    );
+    let data = std::fs::read(&path).expect("read isolated real UnityFS bundle");
+    let parsed = UnityFsParser::new()
+        .parse_bytes(&data)
+        .expect("parse isolated real UnityFS bundle");
+
+    assert_eq!(parsed.header.total_size, data.len() as u64);
+    assert!(!parsed.header.unity_version.is_empty());
+    assert!(!parsed.blocks.is_empty());
+    assert!(!parsed.directories.is_empty());
+    assert_eq!(parsed.files.len(), parsed.directories.len());
+    assert_eq!(
+        parsed.uncompressed_data_size,
+        parsed.files.iter().map(|file| file.size).sum::<u64>()
+    );
+}