feat: add ASCII art email signature and update documentation

- Add signature.txt with stylish VALKNAR banner and contact info
- Update README.md to document the new signature file
- Clean up .gitignore to track signature.txt
- Remove legacy config files (prettier, rubocop, pre-commit, etc.)
- Update arty.yml with additional installation scripts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -284,6 +284,9 @@ rs /local/path/ user@host:/remote/path/
 ### **Orchestration**
 - **`arty.yml`** - Repository and dependency management with installation scripts
 
+### **Personal**
+- **`signature.txt`** - ASCII art email signature with contact information
+
 ---
 
 ## 🔗 HIDRIVE INTEGRATION 🔗