[App Suggestion] Add opencode

[Farhan-25]

Application Link

https://opencode.ai/

Rules Checklist

• This application is popular enough, so is not considered as niche
• This application is not considered bloatware
• This application is free to access
• This application should be included on majority of fresh installed systems
• This application is present on WinGet (check winstall.app or do 'winget search your-app' in terminal)

Check for denied applications

• Yes, I checked PRs, issues and discussions for existing suggestions and their result