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/shell-scripting/skills/bash-defensive-patterns/SKILL.md

@@ -531,9 +531,3 @@ check_dependencies
 12. **Test error paths** - Ensure error handling works correctly
 13. **Use `command -v`** - Safer than `which` for checking executables
 14. **Prefer printf over echo** - More predictable across systems
-
-## Resources
-
-- **Bash Strict Mode**: http://redsymbol.net/articles/unofficial-bash-strict-mode/
-- **Google Shell Style Guide**: https://google.github.io/styleguide/shellguide.html
-- **Defensive BASH Programming**: https://www.lifepipe.net/

plugins/shell-scripting/skills/bats-testing-patterns/SKILL.md

@@ -622,10 +622,3 @@ coverage: test
 8. **Test across shell dialects** - Ensure portability
 9. **Keep tests fast** - Run in parallel when possible
 10. **Document complex test setup** - Explain unusual patterns
-
-## Resources
-
-- **Bats GitHub**: https://github.com/bats-core/bats-core
-- **Bats Documentation**: https://bats-core.readthedocs.io/
-- **TAP Protocol**: https://testanything.org/
-- **Test-Driven Development**: https://en.wikipedia.org/wiki/Test-driven_development

plugins/shell-scripting/skills/shellcheck-configuration/SKILL.md

@@ -448,9 +448,3 @@ shellcheck --format=quiet script.sh
 6. **Update regularly** - Keep ShellCheck current for new checks
 7. **Use pre-commit hooks** - Catch issues locally before pushing
 8. **Integrate with editors** - Get real-time feedback during development
-
-## Resources
-
-- **ShellCheck GitHub**: https://github.com/koalaman/shellcheck
-- **ShellCheck Wiki**: https://www.shellcheck.net/wiki/
-- **Error Code Reference**: https://www.shellcheck.net/