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)/guilds/[id]/forum/[threadId]/page.tsx

@@ -103,11 +103,11 @@ export default async function GuildForumThreadPage({
 	} catch (error) {
 		publicReadFailure("guild.thread")(error);
 		return (
-			<main className="page-grid">
+			<section className="page-grid">
 				<ContentCard>
 					<PublicLoadError href={`/guilds/${guildId}/forum/${threadId}`} />
 				</ContentCard>
-			</main>
+			</section>
 		);
 	}
 
@@ -173,7 +173,7 @@ export default async function GuildForumThreadPage({
 							: null;
 
 	return (
-		<main className="page-grid">
+		<section className="page-grid">
 			{replied === "1" ? (
 				<div role="status" style={feedbackStyle("success")}>
 					{t("success.replied")}
@@ -317,6 +317,6 @@ export default async function GuildForumThreadPage({
 					{t("loginToReply")} <Link href="/login">{t("loginLink")}</Link>
 				</p>
 			)}
-		</main>
+		</section>
 	);
 }

src/app/(site)/guilds/[id]/forum/new/page.tsx

@@ -70,7 +70,7 @@ export default async function NewThreadPage({
 						: null;
 
 	return (
-		<main className="page-grid">
+		<section className="page-grid">
 			{errorMessage ? (
 				<div role="alert" style={feedbackStyle("error")}>
 					{errorMessage}
@@ -132,6 +132,6 @@ export default async function NewThreadPage({
 					</div>
 				</form>
 			</ContentCard>
-		</main>
+		</section>
 	);
 }

src/app/(site)/guilds/[id]/forum/page.tsx

@@ -67,11 +67,11 @@ export default async function GuildForumPage({
 	} catch (error) {
 		publicReadFailure("guild.forum")(error);
 		return (
-			<main className="page-grid">
+			<section className="page-grid">
 				<ContentCard>
 					<PublicLoadError href={`/guilds/${guildId}/forum`} />
 				</ContentCard>
-			</main>
+			</section>
 		);
 	}
 
@@ -135,7 +135,7 @@ export default async function GuildForumPage({
 	const usernameById = new Map(users.map((u) => [u.id, u.username]));
 
 	return (
-		<main className="page-grid">
+		<section className="page-grid">
 			{posted === "1" ? (
 				<div role="status" style={feedbackStyle("success")}>
 					{t("success.posted")}
@@ -240,6 +240,6 @@ export default async function GuildForumPage({
 					</table>
 				)}
 			</ContentCard>
-		</main>
+		</section>
 	);
 }

src/app/(site)/guilds/[id]/page.tsx

@@ -55,11 +55,11 @@ export default async function GuildPage({
 	} catch (error) {
 		publicReadFailure("guild.detail")(error);
 		return (
-			<main className="page-grid">
+			<section className="page-grid">
 				<ContentCard>
 					<PublicLoadError href={`/guilds/${guildId}`} />
 				</ContentCard>
-			</main>
+			</section>
 		);
 	}
 
@@ -139,7 +139,7 @@ export default async function GuildPage({
 	const created = formatDate(new Date(guild.dateCreated * 1000), "date");
 
 	return (
-		<main className="page-grid">
+		<section className="page-grid">
 			<p style={{ margin: 0 }}>
 				<Link href="/guilds">{t("allGuilds")}</Link>
 			</p>
@@ -251,6 +251,6 @@ export default async function GuildPage({
 					</div>
 				)}
 			</ContentCard>
-		</main>
+		</section>
 	);
 }

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

@@ -50,7 +50,7 @@ export default async function GuildsPage() {
 	const guilds = await getGuilds();
 
 	return (
-		<main className="page-grid">
+		<section className="page-grid">
 			<ContentCard icon="🚪" title={t("title")} subtitle={t("subtitle")} />
 
 			<ContentCard padded={!guilds?.length}>
@@ -98,6 +98,6 @@ export default async function GuildsPage() {
 					</div>
 				)}
 			</ContentCard>
-		</main>
+		</section>
 	);
 }