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/components/nav-dropdown.tsx

@@ -1,13 +1,23 @@
 "use client";
 
-import { AnimatePresence, motion } from "motion/react";
+import dynamic from "next/dynamic";
 import Image from "next/image";
 import { type ReactNode, useEffect, useRef, useState } from "react";
-import { dropdownVariants } from "@/lib/motion";
+
+/**
+ * The animated body loads lazily (`motion/react` is ~43 KB gzip and only needed
+ * while a dropdown is open), so public pages pay nothing until the first
+ * interaction.
+ */
+const NavDropdownPanel = dynamic(
+	() => import("@/components/nav-dropdown-panel"),
+	{ ssr: false },
+);
 
 interface NavDropdownProps {
 	label: string;
 	icon?: string;
+	/** Rendered as a link (default) or a menu item (`as="menu"`). */
 	children: ReactNode;
 }
 
@@ -55,13 +65,13 @@ export function NavDropdown({ label, icon, children }: NavDropdownProps) {
 					/>
 				) : null}
 				{label}
-				<motion.svg
-					className="ml-auto md:ml-1 w-3 h-3 shrink-0"
-					animate={{ rotate: open ? 180 : 0 }}
-					transition={{ duration: 0.2 }}
+				<svg
+					className="ml-auto md:ml-1 w-3 h-3 shrink-0 transition-transform duration-200"
+					style={{ transform: open ? "rotate(180deg)" : undefined }}
 					fill="none"
 					stroke="currentColor"
 					viewBox="0 0 24 24"
+					aria-hidden="true"
 				>
 					<path
 						strokeLinecap="round"
@@ -69,22 +79,10 @@ export function NavDropdown({ label, icon, children }: NavDropdownProps) {
 						strokeWidth={2}
 						d="M19 9l-7 7-7-7"
 					/>
-				</motion.svg>
+				</svg>
 			</button>
-			<AnimatePresence>
-				{open && (
-					<motion.div
-						className="dropdown-menu md:absolute left-0 top-full mt-0.5 min-w-0 md:min-w-[200px] rounded-xl z-50 py-2"
-						role="menu"
-						variants={dropdownVariants}
-						initial="hidden"
-						animate="visible"
-						exit="exit"
-					>
-						{children}
-					</motion.div>
-				)}
-			</AnimatePresence>
+			{/* Closed state is plain HTML; the animation loads on first open. */}
+			<NavDropdownPanel open={open}>{children}</NavDropdownPanel>
 		</div>
 	);
 }