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/serve-explorer-local.sh

@@ -1,26 +1,16 @@
-#!/bin/bash
-# Simple local server for explorer (fallback option)
-# Usage: ./serve-explorer-local.sh [port]
+#!/usr/bin/env bash
+# Local static explorer with SPA path fallback (/institution, /compare, /addresses/… → index.html).
+# Usage: SERVE_BIND=0.0.0.0 ./scripts/serve-explorer-local.sh [port]
+# Requires: Python 3.7+
 
-PORT=${1:-8080}
-FRONTEND_DIR="$(cd "$(dirname "$0")/../frontend/public" && pwd)"
+set -euo pipefail
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PORT="${1:-8080}"
+BIND="${SERVE_BIND:-127.0.0.1}"
 
-if [ ! -f "$FRONTEND_DIR/index.html" ]; then
-    echo "❌ Frontend not found at: $FRONTEND_DIR/index.html"
-    exit 1
+if ! command -v python3 >/dev/null 2>&1; then
+  echo "python3 required" >&2
+  exit 1
 fi
 
-echo "Serving explorer on http://localhost:$PORT"
-echo "Frontend: $FRONTEND_DIR"
-
-cd "$FRONTEND_DIR"
-
-# Try Python 3 first, then Python 2
-if command -v python3 >/dev/null 2>&1; then
-    python3 -m http.server "$PORT"
-elif command -v python >/dev/null 2>&1; then
-    python -m SimpleHTTPServer "$PORT"
-else
-    echo "❌ Python not found. Install Python to use this script."
-    exit 1
-fi
+exec python3 "$SCRIPT_DIR/serve_explorer_spa.py" "$PORT" --bind "$BIND"