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/messages/en.json

@@ -991,7 +991,8 @@
 			"confirm": "Confirm",
 			"enableIntro": "Add a second layer of security with an authenticator app.",
 			"enable": "Enable 2FA",
-			"rateLimit": "Too many attempts. Please wait before trying again."
+			"rateLimit": "Too many attempts. Please wait before trying again.",
+			"alreadyEnabled": "Two-factor authentication is already enabled. Disable it first if you want to set it up again."
 		},
 		"login": {
 			"title": "Sign in",
@@ -1021,7 +1022,8 @@
 			"username": "Username",
 			"password": "Password",
 			"registeredSuccess": "Account created — check your inbox for the verification link, then sign in.",
-			"verifyEmailCta": "Request a new verification link"
+			"verifyEmailCta": "Request a new verification link",
+			"passwordChanged": "Your password has been changed. Sign in with your new password."
 		},
 		"register": {
 			"title": "Create account",
@@ -1096,7 +1098,8 @@
 			"emailPlaceholder": "Your email",
 			"sendResetLink": "Send reset link",
 			"backToLogin": "Back to login",
-			"errorCaptcha": "Captcha verification failed. Please try again."
+			"errorCaptcha": "Captcha verification failed. Please try again.",
+			"sendAnotherLink": "Send another link"
 		},
 		"reset": {
 			"title": "Set a new password",
@@ -1105,7 +1108,9 @@
 			"resetPassword": "Reset password",
 			"backToLogin": "Back to login",
 			"passwordMinLength": "Password must be at least 12 characters",
-			"tooManyAttempts": "Too many attempts — try again later"
+			"tooManyAttempts": "Too many attempts — try again later",
+			"invalidLink": "This reset link is invalid or has expired. Request a new one.",
+			"failed": "The password could not be reset. Please try again."
 		},
 		"verify": {
 			"verifiedTitle": "You're all set",