Modernize Holepunch stack for HyperDB 6 and current replication APIs

Align P2NS with current Autopass, Hypercore, Hyperdrive, and Protomux behavior:
add plugin DB recovery for incompatible persisted HyperDB data, stop
unconditional spec rebuilds via fingerprinting, update SDK replication paths,
and align proxy invite channels with p2ns.core-* protocols without replicating
Autopass over the p2ns topic.

docs/plugins/PLUGIN_SDK.md

@@ -1793,7 +1793,7 @@ const updated = sdk.db.updated('@example/members', { name: 'Alice' });
 // Returns: boolean
 
 // Reload the internal snapshot
-sdk.db.reload();
+sdk.db.update(); // refreshes snapshot (HyperDB 6; sdk.db.reload() also calls update())
 
 // Database properties
 if (sdk.db.closed) { /* ... */ }