fix: warn before the delete, not after — plus round-2 copy and a11y corrections

Round 2 on the feature diff (15 → 12):

- still_allowed_by_env now rides the invite LIST as well as the delete response,
  so the confirmation warns while the admin can still change their mind. It
  mattered most for a DENIED row on an env-allow-listed address: deleting it
  silently converted a refusal into a grant, and the only warning arrived after
  the irreversible click.
- Both inbox bodies claimed to name "the most recent" dropped message. The
  throttle records the FIRST of each hour and never updates it, so they now say
  "one of them", and the not-configured body finally names where to fix it.
- settings.invites.emailOff told the admin they "get no notice when someone
  signs up" — rendered directly above the queue that shows exactly that. Only
  the email is lost, and it now says so.
- The disabled delete buttons put their reason out of reach: `disabled` drops a
  control from the tab order and suppresses its title. Switched to
  aria-disabled + preventDefault, the pattern Playlists.tsx already established
  for the same reason.
- deleteInvite is quiet, so the 409 the UI handles with a translated toast no
  longer also raises the server's English detail as a modal.
- After a completed password reset, Back landed on the reset form again with a
  consumed token — the history change made that state reachable. The token is
  cleared on success so the reset view stops being the card's root.
- The hu deleteHasAccount named a tab that renders under a different label.

Tests: a dom test for the Access-requests panel covering both has_account
variants and all three delete outcomes, /api/me flag cases, an ADMIN_EMAILS
case, and the env-allowlist test now patches the raw setting so the parsing
stays under test.

backend/app/routes/admin.py

@@ -44,6 +44,14 @@ def _accounts_for(db: Session, emails: Iterable[str]) -> set[str]:
     return {e.lower() for e in rows if e}
 
 
+def _env_allowed(email: str) -> bool:
+    """Whether the env bootstrap lists still let this address in. `is_allowed` consults them only
+    when no Invite row exists, so this is exactly what deleting the row would fall back to — and the
+    admin has to know that BEFORE they confirm, not from a toast afterwards."""
+    email = (email or "").lower()
+    return email in settings.allowed_email_set or email in settings.admin_email_set
+
+
 def _serialize(inv: Invite, *, has_account: bool = False) -> dict:
     return {
         "id": inv.id,
@@ -55,6 +63,9 @@ def _serialize(inv: Invite, *, has_account: bool = False) -> dict:
         "decided_by": inv.decided_by,
         # Drives the delete affordance: an entry backed by an account is not removable here.
         "has_account": has_account,
+        # …and whether removing it would actually take access away, or leave the env allow-list
+        # granting it anyway (for an ADMIN_EMAILS address, as an admin).
+        "still_allowed_by_env": _env_allowed(inv.email),
     }
 
 
@@ -197,8 +208,7 @@ def delete_invite(
             status_code=409,
             detail="That address already has an account — delete the account instead.",
         )
-    email = (inv.email or "").lower()
-    still_allowed_by_env = email in settings.allowed_email_set or email in settings.admin_email_set
+    still_allowed_by_env = _env_allowed(inv.email)
     audit.record(
         db,
         admin.id,