#35: keep the redesign's source ASCII

The previous commit put four literal non-ASCII characters into source, which
lang-lint rejects (PLAN.md 21.1: all code in English, ASCII-only, enforced by
CI rather than review). Nine lines failed.

The brand mark in the four rails and sign-in cards was a literal lambda, and
the domains screen's meta line joined DMARC, MTA-STS and DANE with a literal
middot. Both are now \u escapes, so the source is ASCII and the rendered page
is unchanged - the served sign-in page emits ce bb for the mark, and the
domains chunk carries the middot as \xb7.

globals.css goes with them. The linter does not scan .css today, so this was
passing, but the stylesheet was the only file in the tree using box-drawing
section rules and em dashes, and there is no reason for it to be the
exception - ASCII hyphens read the same in a comment.

Verified: lang-lint clean, 98 tests green, tsc clean, production build clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

services/webmail/src/app/(auth)/user/login/page.tsx

@@ -59,7 +59,7 @@ export default function UserLoginPage() {
       <div className="w-full max-w-[400px] rounded-2xl bg-dark-panel p-7 shadow-edge">
         <div className="mb-6 flex items-center gap-3">
           <div className="flex h-10 w-10 flex-none items-center justify-center rounded-xl bg-dark-card text-xl leading-none text-indigo-500 shadow-[inset_0_0_0_1px_#9184d9]">
-            λ
+            {"\u03bb"}
           </div>
           <div className="min-w-0">
             <h1 className="text-lg font-medium leading-tight text-slate-100">{t("auth.userLoginTitle")}</h1>