Add WalletConnect stub, track surfaces, legacy SPA retirement, and dual-domain checks.

Publish walletconnect config endpoints, Track 3/4 notes on analytics/operator pages, legacy SPA at /legacy/index.html with root redirect, and a parity verifier for explorer.d-bis.org vs blockscout.defi-oracle.io.

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

scripts/verify/check-explorer-dual-domain-parity.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+PRIMARY_DOMAIN="${PRIMARY_DOMAIN:-https://explorer.d-bis.org}"
+COMPANION_DOMAIN="${COMPANION_DOMAIN:-https://blockscout.defi-oracle.io}"
+
+paths=(
+  "/"
+  "/wallet"
+  "/operations"
+  "/bridge"
+  "/api/v2/stats"
+  "/explorer-api/v1/track1/bridge/status"
+  "/token-aggregation/api/v1/routes/matrix?includeNonLive=true"
+  "/explorer-api/v1/walletconnect/config"
+)
+
+failures=0
+
+check_path() {
+  local domain="$1"
+  local path="$2"
+  local code
+  code="$(curl -ksS -o /dev/null -w '%{http_code}' --max-time 20 "${domain}${path}")"
+  if [[ "$code" =~ ^(200|301|302|307|308)$ ]]; then
+    printf 'OK  %3s  %s%s\n' "$code" "$domain" "$path"
+  else
+    printf 'FAIL %3s  %s%s\n' "$code" "$domain" "$path"
+    failures=$((failures + 1))
+  fi
+}
+
+echo "Checking explorer dual-domain parity"
+echo "Primary:   $PRIMARY_DOMAIN"
+echo "Companion: $COMPANION_DOMAIN"
+echo
+
+for path in "${paths[@]}"; do
+  check_path "$PRIMARY_DOMAIN" "$path"
+  check_path "$COMPANION_DOMAIN" "$path"
+done
+
+echo
+if (( failures > 0 )); then
+  echo "Dual-domain parity check failed ($failures mismatches/non-200)." >&2
+  exit 1
+fi
+
+echo "Dual-domain parity check passed."