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/README.md

@@ -0,0 +1,30 @@
+# Shared Code
+
+This directory contains code shared between web and mobile applications.
+
+## Structure
+
+- **types/** - TypeScript type definitions and interfaces
+- **utils/** - Utility functions and helpers
+- **blockchain/** - Blockchain-related utilities (Polkadot API wrappers, transaction helpers)
+- **constants/** - Shared constants and configuration values
+
+## Usage
+
+Import shared code in your projects:
+
+```typescript
+// Web project
+import { SomeType } from '../shared/types';
+import { someUtil } from '../shared/utils';
+
+// Mobile project
+import { SomeType } from '../shared/types';
+```
+
+## Guidelines
+
+- Keep code framework-agnostic when possible
+- Add comprehensive JSDoc comments
+- Write unit tests for utilities
+- Avoid platform-specific dependencies