fix: fall back to known token list for symbol/name/decimals

When a token's balance entry is missing or incomplete (e.g. not yet
fetched from Blockscout), the address-token view and send view now
fall back to the built-in known token list for symbol, name, and
decimals instead of showing '?'.

Also includes token name in the balance object returned by
fetchTokenBalances so the contract info well can display it.

Fixes #51

src/shared/balances.js

@@ -85,6 +85,7 @@ async function fetchTokenBalances(address, blockscoutUrl, trackedTokens) {
 
             balances.push({
                 address: item.token.address_hash,
+                name: item.token.name || "",
                 symbol: item.token.symbol || "???",
                 decimals: decimals,
                 balance: bal,