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

.gitea/workflows/e2e.yml

@@ -23,9 +23,8 @@ on: [push]
 # Gitea branch protection, which this repo does not configure, so a failure
 # here is a red mark a reviewer has to account for rather than a hard
 # block. Making e2e-chrome a required check is blocked while reports of the
-# Chrome suite failing under load are still open; the "In CI" section of
-# README.md names them. A gate that fails at random teaches people to merge
-# past red.
+# Chrome suite failing under load are still open. A gate that fails at random
+# teaches people to merge past red.
 #
 # Nothing here may pass vacuously. There is no continue-on-error and no
 # `|| true`. Both scripts exit non-zero when docker is missing, when the
@@ -36,8 +35,7 @@ jobs:
     e2e-chrome:
         runs-on: ubuntu-latest
         # Bounds the image build, a cold cache included, and the three Chrome
-        # programs, so a hung browser frees the shared runner. README.md
-        # "In CI" has the measured times.
+        # programs, so a hung browser frees the shared runner.
         timeout-minutes: 40
         steps:
             # actions/checkout v4.2.2, 2026-02-22
@@ -47,8 +45,7 @@ jobs:
     e2e-firefox:
         runs-on: ubuntu-latest
         # Bounds the image build, a cold cache included, and both Firefox
-        # programs, so a hung browser frees the shared runner. README.md
-        # "In CI" has the measured times.
+        # programs, so a hung browser frees the shared runner.
         timeout-minutes: 15
         steps:
             # actions/checkout v4.2.2, 2026-02-22