chore: remove dead exports and share copied view helpers (closes #168)

AddressDetail and AddressToken defined their own isoDate() and
timeAgo(), hiding the shared pair in helpers.js, so a fix there would
not have reached them. The copies were identical and are deleted;
blockieHtml() and tokenLabel(), each defined twice, move to helpers.js.
A new test shows the history rows and the transaction detail view
write the time with the shared pair.

Deleted as never called: explorerLink(), ETHEREUM_SEPOLIA_CHAIN_ID,
getWalletValue() and getTotalValue() with their tests. Home's "Total:"
is the active address's total, as README.md already says.
addressColor() and etherscanAddressUrl() are no longer exported.

Model: opus-5-5

src/popup/views/approval.js

@@ -10,6 +10,7 @@ const {
     attachCopyHandlers,
     onViewLeave,
     formatFee,
+    tokenLabel,
 } = require("./helpers");
 const { state, saveState } = require("../../shared/state");
 const {
@@ -73,17 +74,6 @@ function tokenAmountText(rawAmount, decimals, symbol) {
     };
 }
 
-// The symbol shown for a token line, resolved from the bundled list, the
-// tokens the user tracks, and the explorer's report — the same chain the
-// amount line's scale comes from. Null when no source names one, so the token
-// lines keep saying `Unknown token` for a token nothing knows.
-function tokenLabel(address) {
-    return resolveTokenSymbol(address, {
-        trackedTokens: state.trackedTokens,
-        wallets: state.wallets,
-    });
-}
-
 // Try to decode calldata using known ABIs.
 // Returns { name, description, details } or null.
 function decodeCalldata(data, toAddress) {