fix: decode V4_SWAP command to resolve ERC20 token symbols

The Uniswap Universal Router calldata decoder listed V4_SWAP (0x10) in
command names but never decoded its inner actions to extract token
addresses. This caused all V4 swaps (e.g. USDT→USDC) to display as
'Swap ETH → ETH' because tokenIn/tokenOut defaulted to null, which
tokenInfo() resolved as native ETH.

Added decodeV4Swap() which parses the V4 inner action bytes:
- SETTLE (0x0b) → extracts input token currency address
- TAKE (0x0e) → extracts output token currency address
- SWAP_EXACT_IN/OUT and their SINGLE variants → extracts tokens from
  pool keys and paths, plus amounts

These addresses are then resolved against the known token list
(TOKEN_BY_ADDRESS) to display correct symbols like USDT, USDC, etc.

Fixes #59

src/shared/uniswap.js

@@ -161,6 +161,157 @@ function decodeWrapEth(input) {
     }
 }
 
+// V4 inner action IDs
+const V4_SWAP_EXACT_IN_SINGLE = 0x06;
+const V4_SWAP_EXACT_IN = 0x07;
+const V4_SWAP_EXACT_OUT_SINGLE = 0x08;
+const V4_SWAP_EXACT_OUT = 0x09;
+const V4_SETTLE = 0x0b;
+const V4_TAKE = 0x0e;
+
+// Decode V4_SWAP (command 0x10) input bytes.
+// The input is ABI-encoded as (bytes actions, bytes[] params).
+// We extract token addresses from SETTLE (input) and TAKE (output) sub-actions,
+// and swap amounts from the swap sub-actions.
+function decodeV4Swap(input) {
+    try {
+        const d = coder.decode(["bytes", "bytes[]"], input);
+        const actions = getBytes(d[0]);
+        const params = d[1];
+
+        let settleToken = null;
+        let takeToken = null;
+        let amountIn = null;
+        let amountOutMin = null;
+
+        for (let i = 0; i < actions.length; i++) {
+            const actionId = actions[i];
+            try {
+                if (actionId === V4_SETTLE) {
+                    // SETTLE: (address currency, uint256 maxAmount, bool payerIsUser)
+                    const s = coder.decode(
+                        ["address", "uint256", "bool"],
+                        params[i],
+                    );
+                    settleToken = s[0];
+                } else if (actionId === V4_TAKE) {
+                    // TAKE: (address currency, address recipient, uint256 amount)
+                    const t = coder.decode(
+                        ["address", "address", "uint256"],
+                        params[i],
+                    );
+                    takeToken = t[0];
+                } else if (
+                    actionId === V4_SWAP_EXACT_IN ||
+                    actionId === V4_SWAP_EXACT_IN_SINGLE
+                ) {
+                    // Extract amounts from exact-in swap actions
+                    if (actionId === V4_SWAP_EXACT_IN) {
+                        // ExactInputParams: (address currencyIn,
+                        //   tuple(address,uint24,int24,address,bytes)[] path,
+                        //   uint128 amountIn, uint128 amountOutMin)
+                        try {
+                            const s = coder.decode(
+                                [
+                                    "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
+                                ],
+                                params[i],
+                            );
+                            if (!settleToken) settleToken = s[0][0];
+                            const path = s[0][1];
+                            if (path.length > 0 && !takeToken) {
+                                takeToken = path[path.length - 1][0];
+                            }
+                            if (!amountIn) amountIn = s[0][2];
+                            if (!amountOutMin) amountOutMin = s[0][3];
+                        } catch {
+                            // Fall through — SETTLE/TAKE will provide tokens
+                        }
+                    } else {
+                        // ExactInputSingleParams: (tuple(address,address,uint24,int24,address) poolKey,
+                        //   bool zeroForOne, uint128 amountIn, uint128 amountOutMin, bytes hookData)
+                        try {
+                            const s = coder.decode(
+                                [
+                                    "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
+                                ],
+                                params[i],
+                            );
+                            const poolKey = s[0][0];
+                            const zeroForOne = s[0][1];
+                            if (!settleToken)
+                                settleToken = zeroForOne
+                                    ? poolKey[0]
+                                    : poolKey[1];
+                            if (!takeToken)
+                                takeToken = zeroForOne
+                                    ? poolKey[1]
+                                    : poolKey[0];
+                            if (!amountIn) amountIn = s[0][2];
+                            if (!amountOutMin) amountOutMin = s[0][3];
+                        } catch {
+                            // Fall through
+                        }
+                    }
+                } else if (
+                    actionId === V4_SWAP_EXACT_OUT ||
+                    actionId === V4_SWAP_EXACT_OUT_SINGLE
+                ) {
+                    if (actionId === V4_SWAP_EXACT_OUT) {
+                        try {
+                            const s = coder.decode(
+                                [
+                                    "tuple(address,tuple(address,uint24,int24,address,bytes)[],uint128,uint128)",
+                                ],
+                                params[i],
+                            );
+                            if (!takeToken) takeToken = s[0][0];
+                            const path = s[0][1];
+                            if (path.length > 0 && !settleToken) {
+                                settleToken = path[path.length - 1][0];
+                            }
+                        } catch {
+                            // Fall through
+                        }
+                    } else {
+                        try {
+                            const s = coder.decode(
+                                [
+                                    "tuple(tuple(address,address,uint24,int24,address),bool,uint128,uint128,bytes)",
+                                ],
+                                params[i],
+                            );
+                            const poolKey = s[0][0];
+                            const zeroForOne = s[0][1];
+                            if (!settleToken)
+                                settleToken = zeroForOne
+                                    ? poolKey[0]
+                                    : poolKey[1];
+                            if (!takeToken)
+                                takeToken = zeroForOne
+                                    ? poolKey[1]
+                                    : poolKey[0];
+                        } catch {
+                            // Fall through
+                        }
+                    }
+                }
+            } catch {
+                // Skip sub-actions we can't decode
+            }
+        }
+
+        return {
+            tokenIn: settleToken,
+            tokenOut: takeToken,
+            amountIn,
+            amountOutMin,
+        };
+    } catch {
+        return null;
+    }
+}
+
 // Try to decode a Universal Router execute() call.
 // Returns { name, description, details } matching the format used by
 // the approval UI, or null if the calldata is not a recognised execute().
@@ -233,6 +384,19 @@ function decode(data, toAddress) {
                     }
                 }
 
+                if (cmdId === 0x10) {
+                    const v4 = decodeV4Swap(inputs[i]);
+                    if (v4) {
+                        if (!inputToken && v4.tokenIn) inputToken = v4.tokenIn;
+                        if (!outputToken && v4.tokenOut)
+                            outputToken = v4.tokenOut;
+                        if (!inputAmount && v4.amountIn)
+                            inputAmount = v4.amountIn;
+                        if (!minOutput && v4.amountOutMin)
+                            minOutput = v4.amountOutMin;
+                    }
+                }
+
                 if (cmdId === 0x0c) {
                     hasUnwrapWeth = true;
                 }