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

tests/timestampDisplay.test.js

@@ -1,7 +1,7 @@
 // A transaction's time is written by isoDate() and timeAgo() in
-// src/popup/views/helpers.js on every screen that shows one (README, Display
-// Consistency; https://git.eeqj.de/sneak/AutistMask/issues/168). AddressDetail
-// and AddressToken used to define their own copies, so a fix to the shared pair
+// src/popup/views/helpers.js on every screen that shows one (README, Amounts;
+// https://git.eeqj.de/sneak/AutistMask/issues/168). AddressDetail and
+// AddressToken used to define their own copies, so a fix to the shared pair
 // would not have reached them.
 //
 // The pair is replaced before the views are loaded, because a view takes it