chore: metamask networks, explorer SPA, nginx scripts; ignore Python cache

- Dual-chain / GRU deployment JSON sync
- Frontend explorer SPA + MetaMask components
- Scripts: nginx fixes, link deploy, local SPA serve helper
- Token icon chain-138.png; .gitignore __pycache__

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/deploy-and-verify-link.sh

@@ -154,7 +154,7 @@ if [ "$CONFIRMED" != "true" ]; then
     echo "2. Transaction may have failed"
     echo "3. RPC node may be out of sync"
     echo ""
-    echo "Check block explorer: https://explorer.d-bis.org/address/$ACCOUNT"
+    echo "Check block explorer: https://explorer.d-bis.org/addresses/$ACCOUNT"
     exit 1
 fi