Reorganize repository into monorepo structure

Restructured the project to support multiple frontend applications:
- Move web app to web/ directory
- Create pezkuwi-sdk-ui/ for Polkadot SDK clone (planned)
- Create mobile/ directory for mobile app development
- Add shared/ directory with common utilities, types, and blockchain code
- Update README.md with comprehensive documentation
- Remove obsolete DKSweb/ directory

This monorepo structure enables better code sharing and organized
development across web, mobile, and SDK UI projects.

shared/blockchain/index.ts

@@ -0,0 +1,10 @@
+/**
+ * Blockchain utilities and helpers
+ *
+ * This module provides common blockchain interaction utilities
+ * that can be used across web and mobile applications.
+ */
+
+export * from './polkadot';
+
+// Add more blockchain utility exports as needed