[BUG]: Spell check enabled by default with no option to disable #26112

Description

The input box in the OpenCode client has spell check enabled by default, and there is no option to disable it. This causes red wavy underlines to appear frequently while typing, which is distracting and degrades the user experience.

What happened:

• Spell check is automatically enabled in the chat input box
• Red wavy underlines appear under many words while typing
• There is no visible setting or toggle to disable spell check
• This is particularly annoying when writing code, technical terms, or non-English content

Expected behavior:

• Spell check should be disabled by default, or at least have a clear toggle in settings
• Users should be able to disable spell check if they prefer a clean input experience
• Technical terms, code snippets, and mixed-language input should not trigger spell check warnings

Steps to reproduce:

1. Open OpenCode client
2. Focus on the chat input box
3. Start typing (especially code, technical terms, or mixed content)
4. Observe red wavy underlines appearing under words
5. Try to find a setting to disable spell check - no option available

Environment:

• OS: Windows 11
• OpenCode Version: v1.14.40
• Terminal: Windows Terminal