feat: explorer API, wallet, CCIP scripts, and config refresh

- Backend REST/gateway/track routes, analytics, Blockscout proxy paths.
- Frontend wallet and liquidity surfaces; MetaMask token list alignment.
- Deployment docs, verification scripts, address inventory updates.

Check: go build ./... under backend/ (pass).
Made-with: Cursor

backend/api/track1/endpoints_validation_test.go

@@ -0,0 +1,43 @@
+package track1
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHandleBlockDetailRejectsInvalidBlockNumber(t *testing.T) {
+	server := &Server{}
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/track1/block/not-a-number", nil)
+	w := httptest.NewRecorder()
+
+	server.HandleBlockDetail(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400 for invalid block number, got %d", w.Code)
+	}
+}
+
+func TestHandleTransactionDetailRejectsInvalidHash(t *testing.T) {
+	server := &Server{}
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/track1/tx/not-a-hash", nil)
+	w := httptest.NewRecorder()
+
+	server.HandleTransactionDetail(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400 for invalid tx hash, got %d", w.Code)
+	}
+}
+
+func TestHandleAddressBalanceRejectsInvalidAddress(t *testing.T) {
+	server := &Server{}
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/track1/address/not-an-address/balance", nil)
+	w := httptest.NewRecorder()
+
+	server.HandleAddressBalance(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400 for invalid address, got %d", w.Code)
+	}
+}