deps: vendor regress 字节字面量优化 gate 改逐编译运行时标志 + 惰性物化单元向 IR——utf16 feature 编译期全局 gate 原会关掉全部 regex 的字节 pass 与执行器起始谓词快路径，启用即劣化全部 str 路径；现字节 pass 由 byte_literals 编译参数控制（str IR 传 true 与旧行为逐位一致、单元 IR 传 false），执行器起始谓词分派按输入编码切换（字节输入保留锚定/字节定位快路径、单元输入逐位尝试），单元向 IR 首次 find_from_utf16/find_from_ucs2 时重解析编译并缓存（正则留存源码码点序列），no_opt 标志同路径贯穿；fork 增量边界 = optimizer.rs 两处 cfg 改运行时标志（optimize 降为包装）+ api.rs Regex 两字段与 utf16 两入口改走单元产物 + classicalbacktrack.rs 两处 cfg 去除分派运行时化 + manifest 独立 [workspace] 表与 feature 注释刷新，其余与上游 0.11.1 逐位一致；新增回归钉五则（well-formed 匹配逐一相等/孤立 surrogate 属性命中/代理对 ≡ str 路径/字节指令与起始谓词按 IR 门控/no_opt 贯穿）

third_party/regress/Cargo.toml

@@ -1,3 +1,9 @@
+# Standalone workspace root: this vendored crate is built and tested on its own
+# (standalone `cargo build` / `cargo test` in this directory), not as a member
+# of the host workspace that vendors it. The empty table keeps it out of the
+# parent workspace's member resolution.
+[workspace]
+
 [package]
 name = "regress"
 version = "0.11.1"
@@ -23,7 +29,8 @@ index-positions = []
 # Prohibits all uses of unsafe code, for the paranoid.
 prohibit-unsafe = []
 
-# Enables UTF-16 support. This disables some optimizations, so it should only be used when necessary.
+# Enables UTF-16 support. Byte-literal optimization is decided per compilation
+# (runtime gate), so enabling this feature no longer degrades the str path.
 utf16 = []
 
 # Enables Pattern trait implementation for str::find, str::contains, etc.