feat: implement Nova Base + Pezkuwi Overlay architecture

- Add Nova utils as git submodule (nova-base/)
- Create pezkuwi-overlay/ for Pezkuwi-specific configs
- Add merge-chains.py script to combine Nova + Pezkuwi
- Add update-all.sh for easy syncing
- Add ARCHITECTURE.md documentation

This architecture allows automatic sync with Nova's Polkadot
ecosystem updates while maintaining Pezkuwi customizations.

Pezkuwi chains: 3 (priority)
Nova chains: 98 (auto-synced)

dapps/dapps.json

@@ -1,7 +1,10 @@
 {
   "popular": [
     {
-      "url": "https://app.hydration.net/NOVA"
+      "url": "https://explorer.pezkuwichain.io/"
+    },
+    {
+      "url": "https://app.hydration.net/"
     },
     {
       "url": "https://app.bifrost.io/"