Don't allow escaped chars in smoothly-input

[Magnus93]

\r,\n,\t Should maybe not be allowed in smoothly-input.

Since the input is just one line then at least \n should not be allowed, and using those chars causes bugs when trying to select all:

Screencast.from.2025-06-16.09.38.49.webm

How to recreate:
Copy some text with a new line in it and paste it in the input.

Ctrl+A will not successfully select the select the entire string.

[qijieye]

#1013