Add React frontend and Django backend code

- React components: Dashboard, MemoryCalendar, SearchBox, ToolList
- Django backend structure
- Package configuration files

code/backend/manage.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+import os
+import sys
+
+def main():
+    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'backend.settings')
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError as exc:
+        raise ImportError(
+            "Couldn't import Django."
+        ) from exc
+    execute_from_command_line(sys.argv)
+
+if __name__ == '__main__':
+    main()