Add Börsenag exchanges (DUSA, DUSB, DUSC, DUSD, HAMA, HAMB, HANA, HANB)

- New boersenag.py with support for Düsseldorf, Hamburg, and Hannover exchanges
- Proper .gitignore to exclude venv and temp files

.gitignore

@@ -0,0 +1,48 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# Virtual environments
+venv/
+ENV/
+env/
+.venv/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Environment files
+.env
+.env.local
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+
+# Test data
+*.gz
+!requirements.txt