* feat(opencode): add OpenCode plugin support
Add `--opencode` flag to `rtk init` for installing a global OpenCode
plugin that rewrites Bash/shell commands through `rtk rewrite`.
- New plugin: hooks/opencode-rtk.ts (thin delegator to rtk rewrite)
- New init modes: --opencode (OpenCode only), combinable with Claude modes
- Plugin install/update/remove lifecycle with idempotent writes
- Uninstall cleans up OpenCode plugin alongside Claude Code artifacts
- `rtk init --show` reports OpenCode plugin status
- Replace unreachable!() with bail!() in match exhaustiveness guard
* docs: add OpenCode plugin documentation
- README: OpenCode plugin section, install flags, troubleshooting
- TROUBLESHOOTING: OpenCode-specific checklist
- Update init mode table to reflect Claude Code default
## Problem
Documentation incorrectly promoted the fork over upstream for installation,
creating confusion about which repository is the source of truth.
## Changes
### Installation Instructions
- **README.md**: Restored curl install pointing to upstream (pszymkowiak/rtk)
- **README.md**: Removed "Fork with All Features" section
- **INSTALL.md**: Added curl install, removed fork recommendation
- **TROUBLESHOOTING.md**: All installation paths → upstream
### Repository References
- **README.md**: Removed fork from repo list, issues → rtk-ai/rtk
- **CLAUDE.md**: Removed fork mention from project list
- **CHANGELOG.md**: Repository and issues → rtk-ai/rtk
- **ROADMAP.md**: Installation instructions → upstream curl
### Scripts
- **check-installation.sh**: Install instructions → upstream curl
## Result
All documentation now consistently points to upstream (rtk-ai/rtk, pszymkowiak/rtk)
as the source of truth for installation and issues.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>