fix(narrow): CallGenFd 的 fd_can 改用 int(len(...)) 消除 64->32 隐式窄化

App/lib/core/Gen/Call/CallGenFd.vp

@@ -90,7 +90,7 @@ novirtual class CallGenFd(CallGenBase.CallGenBase):
         fd_tail: mlirlite.Value* = fd_self
         fd_args: list[ast.AST*]* = cl.args
         fd_can: int = 0
-        if fd_args is not None: fd_can = len(fd_args)
+        if fd_args is not None: fd_can = int(len(fd_args))
         for fd_ai in range(fd_can):
             fd_arg: ast.AST* = fd_args.get(fd_ai)
             if fd_arg is not None: