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/app/api/v1/ai/translate/[id]/route.ts

@@ -3,8 +3,9 @@ import { z } from "zod";
 import { and, eq } from "@epicure/db";
 import { db, recipes, recipeIngredients, recipeSteps } from "@epicure/db";
 import { requireSessionOrApiKey } from "@/lib/api-auth";
-import { withAiQuota } from "@/lib/ai/ai-error";
+import { withAiQuota, resolveAiConfigOrError } from "@/lib/ai/ai-error";
 import { translateRecipe } from "@/lib/ai/features/translate-recipe";
+import { withUserKey } from "@/lib/ai/resolve-user-key";
 
 const Schema = z.object({
   targetLanguage: z.string().min(2).max(50),
@@ -35,6 +36,12 @@ export async function POST(req: NextRequest, { params }: Params) {
     return NextResponse.json({ error: "Validation error", issues: parsed.error.issues }, { status: 400 });
   }
 
+  const configResult = await resolveAiConfigOrError(() =>
+    withUserKey(session!.user.id, { provider: parsed.data.provider, model: parsed.data.model })
+  );
+  if (!configResult.ok) return configResult.response;
+  const aiConfig = configResult.data;
+
   const result = await withAiQuota(session!.user.id, session!.user.tier as "free" | "pro", () =>
     translateRecipe(
       {
@@ -44,8 +51,8 @@ export async function POST(req: NextRequest, { params }: Params) {
         steps: recipe.steps,
       },
       parsed.data.targetLanguage,
-      { provider: parsed.data.provider, model: parsed.data.model }
-    )
+      aiConfig
+    ), { skipQuota: aiConfig.isByok }
   );
   if (!result.ok) return result.response;
   const translation = result.data;