feat: add Team billing tier

Widens the tier enum from free/pro to free/pro/team and every
"free" | "pro" cast that assumed exactly two tiers (~30 call sites:
every AI route's withAiQuota/checkAndIncrementTierLimit call, admin
user/invite management, upload quota checks, OpenAPI schemas). Team
sits above Pro with genuinely unlimited recipes/public-recipes (the
-1 sentinel, which Pro doesn't actually use — Pro uses large finite
numbers instead) and a higher AI-call/storage cap. Seeded via
db:seed, editable afterward from Admin > Tiers.

role (user/moderator/admin — permissions) and tier (free/pro/team —
billing limits) stay separate concepts, as they already were; this
does not touch role-based permissions.

Requires migration 0043 to run against a live DB — not applied in
this sandbox (no Docker here); run `pnpm db:migrate` then `pnpm db:seed`.

v0.44.0

apps/web/app/api/v1/admin/users/route.ts

@@ -7,7 +7,7 @@ import { randomBytes, randomUUID } from "crypto";
 import { APIError } from "better-auth";
 
 const VALID_ROLES = ["user", "moderator", "admin"] as const;
-const VALID_TIERS = ["free", "pro"] as const;
+const VALID_TIERS = ["free", "pro", "team"] as const;
 
 export async function POST(req: NextRequest) {
   const { session, response } = await requireAdmin();