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>

commitlint.config.ts

@@ -0,0 +1,11 @@
+import type { UserConfig } from "@commitlint/types";
+
+const Configuration: UserConfig = {
+  extends: ["@commitlint/config-conventional"],
+  rules: {
+    "body-max-length": [1, "always", 100],
+    "body-max-line-length": [1, "always", 100],
+  },
+};
+
+export default Configuration;