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

TODO.md

@@ -45,6 +45,19 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-05: Dead code removed and copied view helpers shared
+  ([#168](https://git.eeqj.de/sneak/AutistMask/issues/168)). AddressDetail and
+  AddressToken each defined their own `isoDate()` and `timeAgo()` in place of
+  the ones in `src/popup/views/helpers.js`, so a fix to the shared pair would
+  not have reached them. The copies were identical; every screen now uses the
+  shared pair. `blockieHtml()` and `tokenLabel()`, each defined twice, live in
+  `helpers.js` too. Removed as never called: `explorerLink()` (the views build
+  explorer links with `explorerUrl()`), `ETHEREUM_SEPOLIA_CHAIN_ID` (the chain
+  id lives in `src/shared/networks.js`), and `getWalletValue()` and
+  `getTotalValue()`: Home's "Total:" is the active address's total, as
+  `README.md` says. `addressColor()` and `etherscanAddressUrl()` are no longer
+  exported. Nothing the user sees changed.
+
 - 2026-10-05: A prompt raised while another approval window has focus opens a
   window of its own ([#290](https://git.eeqj.de/sneak/AutistMask/issues/290)).
   The background centred each approval window on the last focused window, which