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.

web/src/App.css

@@ -0,0 +1,53 @@
+#root {
+  max-width: 1280px;
+  margin: 0 auto;
+  padding: 2rem;
+  text-align: center;
+}
+
+.logo {
+  height: 6em;
+  padding: 1.5em;
+  will-change: filter;
+  transition: filter 300ms;
+}
+
+.logo:hover {
+  filter: drop-shadow(0 0 2em rgba(20, 184, 166, 0.6));
+}
+
+.logo.react:hover {
+  filter: drop-shadow(0 0 2em rgba(20, 184, 166, 0.6));
+}
+
+@keyframes logo-spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+@media (prefers-reduced-motion: no-preference) {
+  a:nth-of-type(2) .logo {
+    animation: logo-spin infinite 20s linear;
+  }
+}
+
+.card {
+  padding: 2em;
+  border-radius: 0.5rem;
+  border: 1px solid rgba(20, 184, 166, 0.1);
+  background-color: rgba(20, 184, 166, 0.02);
+  transition: all 0.3s ease;
+}
+
+.card:hover {
+  border-color: rgba(20, 184, 166, 0.3);
+  box-shadow: 0 4px 12px rgba(20, 184, 166, 0.1);
+}
+
+.read-the-docs {
+  color: #5f7676;
+}