internal/shortcuts(refactor[typing]): Narrow VCS TypeGuard input

why: Avoid unbounded Any in local VCS guard.
what:
- Type is_vcs input as str

Author: tony

src/libvcs/_internal/shortcuts.py

@@ -127,7 +127,7 @@ def create_project(
 
         assert vcs_matches[0].vcs is not None
 
-        def is_vcs(val: t.Any) -> t.TypeGuard[VCSLiteral]:
+        def is_vcs(val: str) -> t.TypeGuard[VCSLiteral]:
             return isinstance(val, str) and val in {"git", "hg", "svn"}
 
         if is_vcs(vcs_matches[0].vcs):