feat: add Pi provider support, fix community health files, recategorize /onboard

- Add first-class Pi (pi.dev) provider with transformer, tests, and build integration
- Fix CODEOWNERS username (@paulbakaus → @pbakaus)
- Add missing providers to issue/PR templates (Copilot, Kiro, OpenCode, Pi)
- Add Pi and OpenCode logos to homepage hero and install sections
- Move /onboard from "system" to "enhancement" category
- Update README and DEVELOP.md with all supported providers

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -100,6 +100,11 @@ cp -r dist/claude-code/.claude/* ~/.claude/
 cp -r dist/opencode/.opencode your-project/
 ```
 
+**Pi:**
+```bash
+cp -r dist/pi/.pi your-project/
+```
+
 **Gemini CLI:**
 ```bash
 cp -r dist/gemini/.gemini your-project/
@@ -142,8 +147,11 @@ Most commands accept an optional argument to focus on a specific area:
 - [Cursor](https://cursor.com)
 - [Claude Code](https://claude.ai/code)
 - [OpenCode](https://opencode.ai)
+- [Pi](https://pi.dev)
 - [Gemini CLI](https://github.com/google-gemini/gemini-cli)
 - [Codex CLI](https://github.com/openai/codex)
+- [VS Code Copilot](https://code.visualstudio.com)
+- [Kiro](https://kiro.dev)
 
 ## Contributing