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>

public/js/data.js

@@ -73,7 +73,7 @@ export const commandCategories = {
   'delight': 'enhancement',
   'extract': 'system',
   'adapt': 'adaptation',
-  'onboard': 'system'
+  'onboard': 'enhancement'
 };
 
 // Skill relationships - now consolidated into frontend-design skill
@@ -102,6 +102,6 @@ export const commandRelationships = {
   'delight': { combinesWith: ['bolder', 'animate'], flow: 'Enhancement: Add personality' },
   'extract': { flow: 'System: Create design system elements' },
   'adapt': { combinesWith: ['normalize', 'clarify'], flow: 'Adaptation: Different devices/contexts' },
-  'onboard': { flow: 'System: Onboarding & empty states' }
+  'onboard': { combinesWith: ['clarify', 'delight'], flow: 'Enhancement: Onboarding & empty states' }
 };