feat: harden atoms-nexst against review findings (37 items)

Second review pass covering security, performance, admin tooling and the
public/room flows. All HIGH and MEDIUM findings from the audit are resolved;
nothing in this commit changes the visible feature set.

Authentication & session security
- CSP is now set on the request headers in the proxy, which is what Next.js
  uses to derive the render nonce, so the nonce is effective.
- 2FA: an already-enabled user cannot re-enroll, the setup endpoint is
  rate-limited per account, and confirmed codes are persisted so the second
  secret no longer silently never applies.
- Password reset revokes the ticket, authTicket and all personal access
  tokens, and bumps the token version so existing sessions die. The same
  revocation is now wired into the staff-side password reset.
- /reset and /verify return a stable error code instead of raw text; the
  mail lookups are ordered by id so duplicates cannot vary between runs.
- Resending the verification mail gets a per-address cooldown on top of the
  per-user limit.
- Issue API tokens with the narrower radio/ticket ability set instead of "*".

Authorization & input handling
- Mid-rank staff can no longer keep dynamically granted non-view admin.*
  permissions: existing grants are revoked by migration and the grant lookup
  is restricted to "%.view". Rank guards use the dynamic super-admin check.
- Alerting a user is permission-checked and audited like the other tools.
- Material mutations (giveCredits/giveDuckets/giveDiamonds, the admin user
  actions route, bulk user actions) are capped and rank-guarded, and bulk
  ids are bounded.
- updateRoom / updateRoomItem write through a field allowlist, and items
  may only be edited through their own room.
- Classnames reaching the filesystem are validated before use so a crafted
  value cannot escape the asset directories.
- The word filter now also covers offline mails, guild forum threads and
  replies, and user mottos.
- Media uploads are validated by magic bytes, /api/media requires the page
  edit permission, APP_URL must be configured once mail is enabled, and the
  diagnostics error route checks the fetch site header.

Admin tooling
- Secret settings render masked and cannot be overwritten with a blank or
  an arbitrary raw key; radio credentials are new password inputs.
- Commandocentrum balance changes are audited.
- Admin list pagination reads the caller's per-page instead of the max, and
  the log exporter caps offset and search length.

Performance
- Catalog translations are cached per module, with a cheap revision hash;
  the public online count uses a stale window instead of hammering the DB.
- The cache warmup now primes the payload the home route actually reads.
- TopHeader batches its queries into one round trip, and LCP avatars load
  eagerly.
- motion/react and sonner are no longer part of the root layout; the nav
  dropdown and mobile nav panels are lazy client chunks. Anonymous visitors
  again get the navigation chrome, and public pages get an edge cacheable
  response.

Accessibility
- Nested <main> elements in phase pages became <section>; the page entrance
  and route progress animations are pure CSS that respect reduced motion.

src/app/(site)/reset/page.tsx

@@ -1,8 +1,26 @@
+import type { Metadata } from "next";
 import { getTranslations } from "next-intl/server";
 import { resetPassword } from "@/actions/password-reset";
 import Link from "@/components/link";
 import { ContentCard } from "@/components/public/ui";
 
+export async function generateMetadata(): Promise<Metadata> {
+	const t = await getTranslations("pages.reset");
+	return {
+		title: t("title"),
+		description: t("subtitle"),
+		// Single-use links: never indexable.
+		robots: { index: false, follow: false },
+	};
+}
+
+const ERROR_KEYS: Record<string, string> = {
+	password: "passwordMinLength",
+	ratelimit: "tooManyAttempts",
+	invalid: "invalidLink",
+	failed: "failed",
+};
+
 export default async function ResetPage({
 	searchParams,
 }: {
@@ -10,9 +28,12 @@ export default async function ResetPage({
 }) {
 	const t = await getTranslations("pages.reset");
 	const { email = "", token = "", error } = await searchParams;
+	// Only codes the action can produce are mapped — anything else stays silent
+	// instead of being echoed back onto our own domain.
+	const errorKey = error ? (ERROR_KEYS[error] ?? null) : null;
 
 	return (
-		<main style={{ maxWidth: 420, margin: "2rem auto" }}>
+		<section style={{ maxWidth: 420, margin: "2rem auto" }}>
 			<ContentCard icon="🔐" title={t("title")} subtitle={t("subtitle")}>
 				<form action={resetPassword} style={{ display: "grid", gap: "0.7rem" }}>
 					<input type="hidden" name="email" value={email} />
@@ -28,15 +49,16 @@ export default async function ResetPage({
 						{t("resetPassword")}
 					</button>
 				</form>
-				{error ? (
+				{errorKey ? (
 					<p
+						role="alert"
 						style={{
 							color: "var(--color-danger)",
 							textAlign: "center",
 							marginBottom: 0,
 						}}
 					>
-						{error}
+						{t(errorKey)}
 					</p>
 				) : null}
 				<p
@@ -46,6 +68,6 @@ export default async function ResetPage({
 					<Link href="/login">{t("backToLogin")}</Link>
 				</p>
 			</ContentCard>
-		</main>
+		</section>
 	);
 }