Add improvements to text editor

[ahuang11]

Description

Adds a few params, namely:

value_input to differentiate from value

selection to capture what the user is selecting (and potentially have the LLM rewrite that portion)

on_keyup to prevent value from being value_input and to prevent breaking changes; mirrors CodeEditor

How Has This Been Tested?

abcdefgg.mp4

AI Disclosure

• This PR contains AI-generated content.
  • I have tested all AI-generated content in my PR.
  • I take responsibility for all AI-generated content in my PR.

Tools and Models: Opus 4.7 for planning and implementation

Checklist

• Tests added and are passing
• Added documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.69%. Comparing base (b69080c) to head (40cc4e2).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8560      +/-   ##
==========================================
+ Coverage   85.65%   85.69%   +0.03%     
==========================================
  Files         350      350              
  Lines       56200    56244      +44     
==========================================
+ Hits        48139    48196      +57     
+ Misses       8061     8048      -13     

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