Fixes

OpenCode: Standardized on plugins/ directory per official docs (#343)

OpenCode's official documentation uses ~/.config/opencode/plugins/ (plural). Our docs previously used plugin/ (singular). While OpenCode accepts both forms, we've standardized on the official convention to avoid confusion.

Changes:

• Renamed .opencode/plugin/ to .opencode/plugins/ in repo structure
• Updated all installation docs (INSTALL.md, README.opencode.md) across all platforms
• Updated test scripts to match

OpenCode: Fixed symlink instructions (#339, #342)

• Added explicit rm before ln -s (fixes "file already exists" errors on reinstall)
• Added missing skills symlink step that was absent from INSTALL.md
• Updated from deprecated use_skill/find_skills to native skill tool references

Full changelog