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/actions/admin-settings.ts

@@ -14,10 +14,19 @@ import {
 import { PERMS } from "@/lib/permissions";
 import { clearOfficialHabboFurnidataCache } from "@/lib/services/habbo-furnidata-cache";
 import { clearBadgeCache } from "@/lib/services/habboassets";
+import {
+	isSecretSettingKey,
+	SECRET_PLACEHOLDER,
+} from "@/lib/services/setting-secrets";
 import { siteSettings } from "@/lib/services/site-settings";
 
 const managedKeySet = new Set(MANAGED_SETTING_KEYS);
 
+// Raw keys only the CMS core is allowed to own. Writing an arbitrary key from
+// the generic "advanced key/value" form previously meant a staff member could
+// overwrite `turnstile_secret`, `force_staff_2fa` or `min_staff_rank`.
+const RAW_SETTING_KEY_RE = /^[a-z0-9][a-z0-9_.-]{0,127}$/;
+
 function normalizeSettingValue(key: string, value: string): string {
 	if (key === HABBO_GAMEDATA_HOTEL_SETTING_KEY) {
 		return normalizeHabboGamedataHotel(value);
@@ -71,11 +80,12 @@ export async function updateSetting(formData: FormData): Promise<void> {
 	const key = String(formData.get("key") ?? "")
 		.normalize("NFC")
 		.trim();
-	const value = normalizeSettingValue(
-		key,
-		String(formData.get("value") ?? "").normalize("NFC"),
-	);
-	if (!key) return;
+	const raw = String(formData.get("value") ?? "").normalize("NFC");
+	if (!key || !RAW_SETTING_KEY_RE.test(key)) return;
+	// Blank on a secret means "keep what is stored", so the UI can render a
+	// placeholder without the risk of wiping the credential.
+	if (isSecretSettingKey(key) && raw === SECRET_PLACEHOLDER) return;
+	const value = isSecretSettingKey(key) ? raw : normalizeSettingValue(key, raw);
 	await db
 		.insert(WebsiteSetting)
 		.values({ key, value })
@@ -90,7 +100,7 @@ export async function createSetting(formData: FormData): Promise<void> {
 	const key = String(formData.get("key") ?? "")
 		.normalize("NFC")
 		.trim()
-		.slice(0, 255);
+		.slice(0, 128);
 	const value = normalizeSettingValue(
 		key,
 		String(formData.get("value") ?? "").normalize("NFC"),
@@ -99,7 +109,17 @@ export async function createSetting(formData: FormData): Promise<void> {
 		.normalize("NFC")
 		.trim()
 		.slice(0, 255);
-	if (!key) return;
+	// Managed keys go through `saveManagedSettings`; anything else must be a
+	// clearly namespaced custom key, and lockout/security settings are never
+	// writable through the free-form form.
+	if (!key || !RAW_SETTING_KEY_RE.test(key)) return;
+	if (
+		key === "force_staff_2fa" ||
+		key === "min_staff_rank" ||
+		key === "maintenance_enabled"
+	) {
+		return;
+	}
 	await db
 		.insert(WebsiteSetting)
 		.values({ key, value, comment: comment || null })