docs: code comments name the headings README has now (closes #724)

The README rewrite renamed or merged several headings that comments still
cited. Each comment now names the current heading. Line number citations of
README become headings too, and one test name drops its line numbers.

The e2e workflow's citations of "In CI" are dropped, because no section has what
they pointed at. Its comment also corrects what it says about required jobs and
open reports.

The comment on withLock() no longer states a Firefox private window exception,
because the manifest keeps the extension out of those windows.

Two comments also take corrections from reviews: the cases with no total in
DeleteAddress's warning, and the screens that say a swap's amount could not be
decoded.

Model: opus-5-5

src/popup/views/approval.js

@@ -319,12 +319,12 @@ function showTxApproval(details) {
             );
         }
         // A swap the decoder read no amount for, such as one whose V4 swap
-        // action could not be read or a V4 exact-out swap. The wait and error
-        // screens say the amount could not be decoded, with no currency after
-        // it, rather than show the transaction's ETH value as the amount. A
-        // swap paid in native ETH keeps that value: it is the ETH the swap
-        // pays (for an exact-out swap, the most it pays), not a figure that
-        // had to be read from the calldata.
+        // action could not be read or a V4 exact-out swap. The wait, success
+        // and error screens say the amount could not be decoded, with no
+        // currency after it, rather than show the transaction's ETH value as
+        // the amount. A swap paid in native ETH keeps that value: it is the
+        // ETH the swap pays (for an exact-out swap, the most it pays), not a
+        // figure that had to be read from the calldata.
         const tokenIn = decoded.details.find((d) => d.label === "Token In");
         if (
             tokenIn &&