Add six new slash command categories with useful developer tools

- Add /documentation category with create-readme-section command
- Add /security category with security-audit and check-best-practices commands
- Add /architecture category with explain-architecture-pattern command
- Add /promptengineering category with convert-to-test-driven-prompt and batch-operations-prompt commands
- Update README.md to document all new slash commands
- Add Bash(mkdir:*) permission to settings.local.json

.claude/settings.local.json

@@ -57,7 +57,8 @@
       "WebFetch(domain:docs.anthropic.com)",
       "WebFetch(domain:github.com)",
       "WebFetch(domain:openrouter.ai)",
-      "WebFetch(domain:www.comet.com)"
+      "WebFetch(domain:www.comet.com)",
+      "Bash(mkdir:*)"
     ],
     "deny": []
   }