chore(smoke): preflight sepolia balance before membership tx

scripts/e2e-membership-flow.cjs

@@ -116,10 +116,34 @@ async function main() {
     data: quote.calldata,
     value: quote.value,
   };
+
+  const value = ethers.BigNumber.from(txReq.value || "0x0");
+  const feeData = await provider.getFeeData();
+  const configuredGasPrice = GAS_PRICE_WEI ? ethers.BigNumber.from(GAS_PRICE_WEI) : null;
+  const effectiveGasPrice =
+    configuredGasPrice || feeData.gasPrice || feeData.maxFeePerGas || ethers.BigNumber.from("0");
+  const gasUnitsReserve = ethers.BigNumber.from("250000");
+  const estimatedGasCost = effectiveGasPrice.mul(gasUnitsReserve);
+  const totalNeeded = value.add(estimatedGasCost);
+  const balance = await provider.getBalance(address);
+  if (balance.lt(totalNeeded)) {
+    const deficit = totalNeeded.sub(balance);
+    throw new Error(
+      [
+        "insufficient funded balance for membership mint preflight",
+        `balance_wei=${balance.toString()}`,
+        `required_min_wei=${totalNeeded.toString()}`,
+        `deficit_wei=${deficit.toString()}`,
+        `mint_value_wei=${value.toString()}`,
+        `gas_reserve_wei=${estimatedGasCost.toString()}`,
+      ].join(" ")
+    );
+  }
+
   const txRequest = {
     to: txReq.to,
     data: txReq.data,
-    value: txReq.value,
+    value: value,
   };
   if (GAS_PRICE_WEI) {
     txRequest.gasPrice = ethers.BigNumber.from(GAS_PRICE_WEI);