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/developer-essentials/skills/auth-implementation-patterns/SKILL.md

@@ -636,12 +636,3 @@ app.use("/api/", apiLimiter);
 - **Insecure Password Reset**: Use secure tokens with expiration
 - **No Rate Limiting**: Vulnerable to brute force
 - **Trusting Client Data**: Always validate on server
-
-## Resources
-
-- **references/jwt-best-practices.md**: JWT implementation guide
-- **references/oauth2-flows.md**: OAuth2 flow diagrams and examples
-- **references/session-security.md**: Secure session management
-- **assets/auth-security-checklist.md**: Security review checklist
-- **assets/password-policy-template.md**: Password requirements template
-- **scripts/token-validator.ts**: JWT validation utility