REPL adds syntax highlighting to echoed stdin being read in via `input`

Bug report

Bug description:

When obtaining input using the input function, syntax highlighting is being applied on the echoed stdin.
Notably this does not occur when reading input via sys.stdin.read.

tested on nix and uv builds of python3.14 - though I doubt it has any effect with regard to this issue

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-142036

在 Linux 上使用 Python 3.14，通过将 input 与 sys.stdin.read 进行比较来复现该行为。检查 REPL 对回显 stdin 的处理，并确定为什么语法高亮仅应用于 input。当来自 input 的回显 stdin 在没有语法高亮的情况下显示，同时现有的 sys.stdin.read 行为保持不变时，即表示完成。