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.

The e2e workflow's citations of "In CI" are dropped, because no section has what
they pointed at.

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/e2e/run.js

@@ -1280,7 +1280,7 @@ test("the correct password reveals the full phrase, and nothing logs it (#161)",
         );
         assert(!promptShown, "the password prompt is still shown after unlock");
 
-        // Full Identifiers Policy: shown whole, and copyable.
+        // README, ShowRecoveryPhrase: shown whole, and copyable.
         const title = await env.page.getAttribute(
             "#show-phrase-value",
             "title",
@@ -2255,7 +2255,7 @@ async function waitForFilledFlashLine(page) {
     }
 }
 
-// README, No Layout Shift: the rejection message goes into #flash-msg,
+// README, Appearance: the rejection message goes into #flash-msg,
 // whose min-h-[1.25rem] reserves exactly ONE line at text-xs, and which
 // cuts a message too long for that line with an ellipsis rather than wrap
 // it. This shows the real message and measures that nothing moves; the
@@ -2603,7 +2603,7 @@ function toHexWei(wei) {
 }
 
 // A fee in wei as the confirmation screen writes it: truncated to four decimal
-// places (README.md, Display Consistency). Deliberately a second
+// places (README.md, Amounts). Deliberately a second
 // implementation rather than an import of src/shared/amountDisplay.js:
 // asserting against an independent rendering is stronger than asserting a
 // function equals itself. The fixture's fees are above 0.0001 ETH, so the
@@ -3298,7 +3298,7 @@ async function goToTokenConfirm(env) {
         amount: TOKEN_AMOUNT,
     });
     await waitForEstimate(env.page);
-    // TOKEN_AMOUNT to four decimal places (README.md, Display Consistency).
+    // TOKEN_AMOUNT to four decimal places (README.md, Amounts).
     const shown = await shownAmount(env.page);
     assert(
         shown === "0.2500 " + STUB_TOKEN.symbol,
@@ -3453,7 +3453,7 @@ test("a token that lies about decimals() at signing time broadcasts nothing (#30
 
 // ------------------------- a send Sign & Send refuses moves nothing (#583)
 //
-// README, No Layout Shift. Sign & Send refuses a send on the confirmation
+// README, Appearance. Sign & Send refuses a send on the confirmation
 // screen when the active network changed since review and when its gas limit
 // or fee is over its bound, and each refusal's sentence sits in a box that held
 // its space from the first paint. This drives the total fee refusal, the longer