Add Mailing lists to Administration

A mailing list is an address that passes mail on to everyone on it. To
Stalwart it is its own object, x:MailingList, behind sysMailingList*, so
it gets its own section under Directory after Groups: search, fifty to a
page with each list's recipient count, and a panel to create, edit and
delete one.

Recipients are a property of the list, so unlike a group's members they
save with the rest of the panel. What Save sends for them is only what was
added and removed, one recipients/<address> pointer each -- the patch the
live server accepted -- so a recipient added elsewhere while the panel was
open is not taken out. They can be pasted several at a time, from a
spreadsheet column, a comma-separated line or Name <address>; anything with
an @ that is not an address stays in the box with a note. Past a dozen, a
filter narrows them.

That is all a list is in Stalwart -- no owners, moderation or posting
rules -- so that is all the panel offers.

The mock answers x:MailingList with two lists, the recipient set's live
shape, and the refusals a wrong address, a clash with an account and a
missing permission get.

Twenty-five new strings and one plural, in all nine catalogues.

web/src/views/admin/AdminNav.tsx

@@ -1,6 +1,6 @@
 import type { ReactNode } from "react";
 import { Link, useLocation } from "wouter";
-import { Globe, LayoutDashboard, User, UsersRound } from "lucide-react";
+import { Globe, LayoutDashboard, List, User, UsersRound } from "lucide-react";
 import { adminSections, type AdminSection } from "@/lib/adminAccess";
 import { t } from "@/lib/i18n";
 import { usePermissions } from "./usePermissions";
@@ -9,6 +9,7 @@ export const ADMIN_SECTIONS: Record<AdminSection, { group: string; label: string
   dashboard: { group: "Overview", label: "Dashboard", icon: <LayoutDashboard size={20} /> },
   accounts: { group: "Directory", label: "Accounts", icon: <User size={20} /> },
   groups: { group: "Directory", label: "Groups", icon: <UsersRound size={20} /> },
+  lists: { group: "Directory", label: "Mailing lists", icon: <List size={20} /> },
   domains: { group: "Mail", label: "Domains", icon: <Globe size={20} /> },
 };