fix: federation peer-joined updates empty onion addresses

When a node was already known (via link-node) but had an empty onion
address, the peer-joined handler returned early without updating the
onion. Now it patches missing onion/pubkey fields on existing nodes.

Also adds update_node() to federation storage and updates the
architecture comparison doc with system resources, StartOS/umbrelOS
tabs, Web5 section, and comparison view.

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

core/archipelago/src/federation/mod.rs

@@ -12,7 +12,7 @@ mod types;
 // Re-export all public items so `crate::federation::*` continues to work.
 pub use invites::{accept_invite, create_invite};
 pub use storage::{
-    add_node, load_nodes, remove_node, save_nodes, set_trust_level,
+    add_node, load_nodes, remove_node, save_nodes, set_trust_level, update_node,
 };
 pub use sync::{build_local_state, deploy_to_peer, sync_with_peer};
 pub use types::{AppStatus, FederatedNode, NodeStateSnapshot, TrustLevel};