feat: expand confirm-tx warnings — closes #114

- Refactor address warnings into src/shared/addressWarnings.js module
  - getLocalWarnings(address, options): sync checks against local lists
  - getFullWarnings(address, provider, options): async local + RPC checks
- Expand scam address list from 652 to 2417 addresses
  - Added EtherScamDB (MIT) as additional source
- Update confirmTx.js to use the new addressWarnings module

src/shared/constants.js

@@ -20,6 +20,19 @@ const ERC20_ABI = [
     "function approve(address spender, uint256 amount) returns (bool)",
 ];
 
+// Known null/burn addresses that permanently destroy funds.
+const BURN_ADDRESSES = new Set([
+    "0x0000000000000000000000000000000000000000",
+    "0x0000000000000000000000000000000000000001",
+    "0x000000000000000000000000000000000000dead",
+    "0xdead000000000000000000000000000000000000",
+    "0x00000000000000000000000000000000deadbeef",
+]);
+
+function isBurnAddress(address) {
+    return BURN_ADDRESSES.has(address.toLowerCase());
+}
+
 module.exports = {
     DEBUG,
     DEBUG_MNEMONIC,
@@ -28,4 +41,6 @@ module.exports = {
     DEFAULT_BLOCKSCOUT_URL,
     BIP44_ETH_PATH,
     ERC20_ABI,
+    BURN_ADDRESSES,
+    isBurnAddress,
 };