fix(skills): remove phantom resource references and fix CoC links (#447)

Remove references to non-existent resource files (references/, assets/,
scripts/, examples/) from 115 skill SKILL.md files. These sections
pointed to directories and files that were never created, causing
confusion when users install skills.

Also fix broken Code of Conduct links in issue templates to use
absolute GitHub URLs instead of relative paths that 404.

plugins/payment-processing/skills/stripe-integration/SKILL.md

@@ -490,33 +490,3 @@ def test_payment_flow():
 
     assert confirmed.status == 'succeeded'
 ```
-
-## Resources
-
-- **references/checkout-flows.md**: Detailed checkout implementation
-- **references/webhook-handling.md**: Webhook security and processing
-- **references/subscription-management.md**: Subscription lifecycle
-- **references/customer-management.md**: Customer and payment method handling
-- **references/invoice-generation.md**: Invoicing and billing
-- **assets/stripe-client.py**: Production-ready Stripe client wrapper
-- **assets/webhook-handler.py**: Complete webhook processor
-- **assets/checkout-config.json**: Checkout configuration templates
-
-## Best Practices
-
-1. **Always Use Webhooks**: Don't rely solely on client-side confirmation
-2. **Idempotency**: Handle webhook events idempotently
-3. **Error Handling**: Gracefully handle all Stripe errors
-4. **Test Mode**: Thoroughly test with test keys before production
-5. **Metadata**: Use metadata to link Stripe objects to your database
-6. **Monitoring**: Track payment success rates and errors
-7. **PCI Compliance**: Never handle raw card data on your server
-8. **SCA Ready**: Implement 3D Secure for European payments
-
-## Common Pitfalls
-
-- **Not Verifying Webhooks**: Always verify webhook signatures
-- **Missing Webhook Events**: Handle all relevant webhook events
-- **Hardcoded Amounts**: Use cents/smallest currency unit
-- **No Retry Logic**: Implement retries for API calls
-- **Ignoring Test Mode**: Test all edge cases with test cards