add guestbook and moderation

crates/concord/src/store.rs

@@ -118,6 +118,8 @@ pub struct CommunityState {
     pub relays: Vec<RelayUrl>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub heads: Vec<EntityHead>,
+    #[serde(default, skip_serializing_if = "BTreeSet::is_empty")]
+    pub banned: BTreeSet<PublicKey>,
     pub added_at_ms: u64,
 }
 
@@ -183,6 +185,7 @@ impl CommunityState {
             channels,
             relays,
             heads,
+            banned: BTreeSet::new(),
             added_at_ms,
         })
     }
@@ -200,6 +203,7 @@ impl CommunityState {
 
     pub fn apply_fold(&mut self, fold: &ControlFold) {
         self.heads = fold.floors.values().cloned().collect();
+        self.banned = fold.banned.clone();
 
         if let Some(community) = &fold.community {
             self.relays = community