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/auth/turbo.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "https://turborepo.org/schema.json",
+  "extends": ["//"],
+  "tasks": {
+    "db:generate": {
+      "cache": false
+    },
+    "db:seed": {
+      "cache": false
+    }
+  }
+}