Keyboard Manager: Support ENTER key in remap to text string

### Description of the new feature / enhancement

Request the ability to include the ENTER key when remapping a shortcut to send a text string. Currently, when remapping a key/shortcut to send text, there is no straightforward way to include an ENTER key press at the end of or within the text output.

### Scenario when this would be used?

This would be useful for automation workflows where you want to:

- Remap a shortcut to send a text string followed by pressing ENTER to submit a form or command
- Create quick text insertions with automatic line breaks or submissions
- Streamline repetitive data entry tasks in applications that require text input followed by confirmation
- For example: Remap Ctrl+Shift+M to send "Example Text" followed by pressing ENTER, all in one action.

Expected Behavior:
When creating a "Send Text" remap, there should be an option to append non-printable keys (specifically ENTER, but ideally TAB, SPACE, and other special keys) to the text string, so they execute after the text is sent.

### Supporting information

This feature would complement existing remapping functionality and help bridge the gap between simple text remaps and more complex automation scenarios without requiring third-party tools like AutoHotkey.

No files, tests, or entry points are mentioned. Start by locating the Keyboard Manager "Send Text" remapping flow and determine how text output and key presses are represented; done means a remap can send text followed by ENTER, with coverage for the requested behavior.

Written by the indexing model from the issue text.