feat(mesh): show federated Archipelago nodes on the Mesh Map

Peers that opt in via a new "Share Location" toggle in Settings
(server.set-location RPC) get plotted on other trusted peers' Mesh Map
with a distinct Archy-logo marker, separate from raw LoRa radio peers.
Location is persisted locally, carried in NodeStateSnapshot, and
propagated through federation sync/delta like other node state.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

core/archipelago/src/federation/sync.rs

@@ -208,6 +208,7 @@ async fn merge_transitive_peers(
 /// and route directly over FIPS from now on). Only peers we trust are
 /// shared — an Untrusted/Observer node should not be re-exported
 /// through us to the network.
+#[allow(clippy::too_many_arguments)]
 pub fn build_local_state(
     apps: Vec<AppStatus>,
     cpu: f64,
@@ -221,6 +222,9 @@ pub fn build_local_state(
     nostr_npub: Option<String>,
     own_fips_npub: Option<String>,
     federated_peers: &[FederatedNode],
+    // Only Some when the node has opted in via server.set-location's
+    // `share` flag — see NodeStateSnapshot::lat/lon's doc comment.
+    shared_location: Option<(f64, f64)>,
 ) -> NodeStateSnapshot {
     let hints = federated_peers
         .iter()
@@ -248,6 +252,8 @@ pub fn build_local_state(
         nostr_npub,
         own_fips_npub,
         federated_peers: hints,
+        lat: shared_location.map(|(lat, _)| lat),
+        lon: shared_location.map(|(_, lon)| lon),
     }
 }
 
@@ -341,12 +347,14 @@ mod tests {
             None,
             None,
             &[],
+            None,
         );
         assert_eq!(state.apps.len(), 1);
         assert_eq!(state.cpu_usage_percent, Some(25.5));
         assert_eq!(state.tor_active, Some(true));
         assert_eq!(state.node_name, Some("Test Node".to_string()));
         assert!(state.federated_peers.is_empty());
+        assert_eq!(state.lat, None);
     }
 
     #[test]
@@ -392,7 +400,7 @@ mod tests {
                 last_transport_at: None,
             },
         ];
-        let state = build_local_state(vec![], 0.0, 0, 0, 0, 0, 0, true, None, None, None, &peers);
+        let state = build_local_state(vec![], 0.0, 0, 0, 0, 0, 0, true, None, None, None, &peers, None);
         assert_eq!(state.federated_peers.len(), 1);
         assert_eq!(state.federated_peers[0].did, "did:key:zTrusted");
         assert_eq!(