fix: a popup reload mid-refresh no longer logs the requests it cancels (closes #218)

Chrome cancels a closing popup's open requests just after pagehide, and in
the page a cancelled fetch() fails with the same "Failed to fetch" as a
server that cannot be reached. The home screen's transaction list and the
balance refresh logged an error for each, and the e2e suite failed on them.

The popup now aborts an AbortController on pagehide, and those failure
reports check its signal first. End-to-end tests reload the popup with
Blockscout held and require nothing logged, and fail the transaction list
for real and require the failure reported; a unit test covers the balance
refresh. The address and token screens and the new-wallet address scan are
#475.

Model: opus-5-5

src/popup/views/home.js

@@ -225,6 +225,9 @@ async function loadHomeTxs(ctx) {
         homeTxs = merged.slice(0, 25);
         renderHomeTxList(ctx);
     } catch (e) {
+        // Cancelled by the popup closing, not failed: see pageClosed in
+        // src/popup/index.js.
+        if (ctx.pageClosed.aborted) return;
         log.errorf("loadHomeTxs failed:", e.message);
         const list = $("home-tx-list");
         if (list) {