Increase max limit of ChatAreaInput

[ahuang11]

I think the original default, inherited from _TextInputBase is too limiting.

This increases it by 10x, so about 12k tokens?

Based on

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.23%. Comparing base (ad154df) to head (c6d3074).
Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #7562       +/-   ##
===========================================
+ Coverage   71.90%   82.23%   +10.32%     
===========================================
  Files         338      339        +1     
  Lines       51441    51477       +36     
===========================================
+ Hits        36990    42332     +5342     
+ Misses      14451     9145     -5306     

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