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>

apps/web/src/app/layout.tsx

@@ -0,0 +1,15 @@
+import "~/assets/styles/globals.css";
+import { DEFAULT_VIEWPORT, DEFAULT_METADATA } from "~/lib/metadata";
+
+export const viewport = DEFAULT_VIEWPORT;
+export const metadata = DEFAULT_METADATA;
+
+// Since we have a `not-found.tsx` page on the root, a layout file
+// is required, even if it's just passing children through.
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return children;
+}