fix(api): raise Fastify body size limit for AI menu photo uploads

Default 1 MiB limit rejected base64-encoded camera photos before the
request handler ever ran ("Request body is too large"), unrelated to
the OpenAI model. Also adds the public domains RLS policy needed for
custom-domain resolution on the public menu page (already applied
manually via SQL Editor, committing for history).

supabase/migrations/20260820000000_public_domain_resolution.sql

@@ -0,0 +1,16 @@
+-- Custom domain resolution needs to be readable by anon so the public web
+-- app (apps/web/src/app/menu/[slug]/page.tsx) can map an arbitrary incoming
+-- hostname -> restaurant without going through the API. Scoped to verified
+-- domains on restaurants that actually have a published menu, matching the
+-- same pattern as the restaurants/locations public policies.
+
+create policy "anyone can resolve verified custom domains" on domains
+  for select using (
+    status = 'verified'
+    and exists (
+      select 1
+      from locations l
+      join menus m on m.location_id = l.id
+      where l.restaurant_id = domains.restaurant_id and m.is_published = true
+    )
+  );