feat(db): mesh data model — meshes, members, invites, audit log

- pgSchema "mesh" with 4 tables isolating the peer mesh domain
- Enums: visibility, transport, tier, role
- audit_log is metadata-only (E2E encryption enforced at broker/client)
- Cascade on mesh delete, soft-delete via archivedAt/revokedAt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/billing/src/lib/schema.ts

@@ -0,0 +1,18 @@
+import * as z from "zod";
+
+export const checkoutSchema = z.object({
+  price: z.object({
+    id: z.string(),
+  }),
+  redirect: z.object({
+    success: z.url(),
+    cancel: z.url(),
+  }),
+});
+
+export const getBillingPortalSchema = z.object({
+  redirectUrl: z.url(),
+});
+
+export type CheckoutPayload = z.infer<typeof checkoutSchema>;
+export type GetBillingPortalPayload = z.infer<typeof getBillingPortalSchema>;