security: fix full audit findings (v0.32.0)

Full list of the audit's confirmed findings and their fixes:

- Stored XSS via unescaped JSON-LD on the public recipe page
  (app/r/[id]/page.tsx) — escape < before injecting.
- CSP allowed unsafe-eval in production — now dev-only (Next prod
  never eval()s; only its HMR does).
- avatarUrl accepted any URL with no ownership check — now takes an
  avatarKey issued by avatar-presign, validated server-side, same
  pattern as recipe/review photos.
- No session revocation on password change/reset — both now revoke
  other sessions (revokeOtherSessions: true, revokeSessionsOnPasswordReset).
- Rate-limit bypass via spoofable X-Forwarded-For — take the last
  (proxy-appended) hop instead of the first (client-supplied) one,
  matching the single-Traefik-hop topology.
- Webhook signing secrets stored plaintext — now AES-256-GCM
  encrypted like every other secret in this app, with a legacy-
  plaintext fallback for pre-existing rows (bare hex has no ":", our
  ciphertext format always does).
- Better Auth's own rate limiter defaulted to in-memory storage,
  ineffective across replicas — now backed by the same Redis as
  lib/rate-limit.ts (secondaryStorage), with storeSessionInDatabase
  explicit so session storage itself doesn't move as a side effect.
- Presigned upload URLs didn't bind the declared file size to the
  actual upload, letting a client under-declare size (and quota
  charge) then PUT an arbitrarily large object — switched to S3
  presigned POST with a signed content-length-range condition,
  enforced by the storage server itself.
- generateMetadata() on the recipe page skipped the visibility
  filter the page body uses, leaking a private recipe's title via
  <title> to any signed-in user with the id.
- Block/unblock had no rate limit, unlike follow/unfollow.
- AI quota was charged even when a user's own BYOK key was used
  (their own credentials/billing) — added an isByok flag through
  the config-resolution chain and skip the charge when set. Also
  wired BYOK into generate/generate-from-idea/translate/import-url,
  which never looked it up at all before.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/components/settings/avatar-uploader.tsx

@@ -6,6 +6,7 @@ import { toast } from "sonner";
 import { Camera, Loader2, X } from "lucide-react";
 import { Avatar, AvatarImage, AvatarFallback } from "@/components/ui/avatar";
 import { Button } from "@/components/ui/button";
+import { uploadToPresignedPost } from "@/lib/upload-client";
 
 export function AvatarUploader({
   name,
@@ -37,22 +38,27 @@ export function AvatarUploader({
         toast.error(err.error ?? t("avatarUploadFailed"));
         return;
       }
-      const { url } = await presignRes.json() as { url: string; key: string };
-      await fetch(url, { method: "PUT", body: file, headers: { "Content-Type": file.type } });
+      const { url, fields, key } = await presignRes.json() as { url: string; fields: Record<string, string>; key: string };
+      const uploaded = await uploadToPresignedPost(url, fields, file);
+      if (!uploaded) {
+        toast.error(t("avatarUploadFailed"));
+        return;
+      }
 
-      // The presigned PUT URL is already publicUrl/bucket/key with query-string
-      // signing params appended — strip those to get the plain public GET URL.
+      // Send back the storage key we were issued, not a client-derived URL —
+      // the server validates the key belongs to us and builds the public URL
+      // itself, so a client can't set avatarUrl to an arbitrary/unowned target.
       const saveRes = await fetch("/api/v1/users/me", {
         method: "PATCH",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ avatarUrl: url.split("?")[0] }),
+        body: JSON.stringify({ avatarKey: key }),
       });
       if (!saveRes.ok) {
         toast.error(t("avatarUploadFailed"));
         return;
       }
       const saved = await saveRes.json() as { avatarUrl?: string };
-      onChange(saved.avatarUrl ?? url.split("?")[0]!, true);
+      onChange(saved.avatarUrl ?? null, true);
       toast.success(t("avatarUploadSuccess"));
     } finally {
       setUploading(false);

apps/web/components/settings/security-form.tsx

@@ -59,7 +59,7 @@ export function SecurityForm({
       const { error } = await authClient.changePassword({
         currentPassword,
         newPassword,
-        revokeOtherSessions: false,
+        revokeOtherSessions: true,
       });
       if (error) {
         toast.error(error.message ?? t("passwordChangeFailed"));