fix(auth): a Google connect names its tab's account too, and a refused tab says why

- /auth/google/connect is a navigation and carries no headers: the tab names the account it
  was built for in `expect`, checked by the same comparison as the request header
  (built_for_another_account); a mismatch lands on /?account=changed
- the link marker names the OAuth state of its own flow: an older flow coming back no longer
  spends the marker of the connect still open (which then returned as a plain sign-in)
- a 401 account_changed reloads the tab with a one-time flag, and the reloaded tab says it
  now shows the account signed in
- a refused switch to a suspended or not-yet-approved account says so in the signed-in
  app's words, naming the address a request was recorded for
- the prefs merge locks FOR NO KEY UPDATE, so a transaction that only added a row referring
  to the account does not hold the save up; a test pins the lock
- giving up a lost page closes a channel page open over it
- e2e README names the chromium-only specs

frontend/src/i18n/locales/en/header.json

@@ -32,6 +32,9 @@
     "signOut": "Sign out",
     "signInAsOther": "Sign in as someone else",
     "switchNotApproved": "That Google account isn't approved for this instance yet, so you're still signed in as before.",
+    "switchSuspended": "That account is suspended, so you're still signed in as before.",
+    "switchRequested": "We recorded an access request for {{email}}. Until an admin approves it, you're still signed in as before.",
+    "tabSwitched": "This tab was showing another account, so it reloaded as the one signed in now.",
     "googleAddress": "Google account: {{email}}",
     "activity": "Activity"
   },

frontend/src/i18n/locales/hu/header.json

@@ -32,6 +32,9 @@
     "signOut": "Kijelentkezés",
     "signInAsOther": "Belépés más fiókkal",
     "switchNotApproved": "Ez a Google-fiók még nincs jóváhagyva ezen a példányon, ezért továbbra is az eddigi fiókkal vagy belépve.",
+    "switchSuspended": "Az a fiók fel van függesztve, ezért továbbra is az eddigi fiókkal vagy belépve.",
+    "switchRequested": "Rögzítettük a hozzáférési kérelmet ehhez a címhez: {{email}}. Amíg egy admin jóvá nem hagyja, továbbra is az eddigi fiókkal vagy belépve.",
+    "tabSwitched": "Ez a fül egy másik fiókot mutatott, ezért újratöltött az éppen bejelentkezett fiókkal.",
     "googleAddress": "Google-fiók: {{email}}",
     "activity": "Napló"
   },