Adds OpenCode support for AI-assisted development, including custom
commands and skills to help contributors maintain consistency and
streamline common workflows.
#### Changes
- Added "AI-Assisted Development with OpenCode" section to
CONTRIBUTING.md with:
- Installation instructions and provider configuration
- Documentation for 8 custom commands (/implement, /continue,
/interview, /document, /commit, /create-plan, /create-scratch,
/create-justification)
- Typical workflow guide
- Clear policy that AI-generated code must be reviewed before submission
- Added .agents/ directory for plans, scratches, and justifications
- Added .opencode/ commands and skills for the agent
- Added helper scripts for creating agent files
