initial hashtag query

Signed-off-by: William Casarin <jb55@jb55.com>

damus/ContentView.swift

@@ -248,6 +248,7 @@ struct ContentView: View {
                     thread_open = true
                 }
             case .filter:
+                
                 break
                 // TODO: handle filter searches?
             }

damus/Nostr/NostrFilter.swift

@@ -15,16 +15,22 @@ struct NostrFilter: Codable {
     var since: Int64?
     var until: Int64?
     var authors: [String]?
+    var hashtag: [String]? = nil
 
     private enum CodingKeys : String, CodingKey {
         case ids
         case kinds
         case referenced_ids = "#e"
         case pubkeys = "#p"
+        case hashtag = "#hashtag"
         case since
         case until
         case authors
     }
+    
+    public static func filter_hashtag(_ htags: [String]) -> NostrFilter {
+        return NostrFilter(ids: nil, kinds: nil, referenced_ids: nil, pubkeys: nil, since: nil, until: nil, authors: nil, hashtag: htags)
+    }
 
     public static var filter_text: NostrFilter {
         return filter_kinds([1])

damus/Nostr/NostrLink.swift

@@ -92,5 +92,9 @@ func decode_nostr_uri(_ s: String) -> NostrLink? {
             return
         }
     
+    if parts.count >= 3 && parts[1] == "hashtag" {
+        return .filter(NostrFilter.filter_hashtag([parts[2]]))
+    }
+    
     return tag_to_refid(parts).map { .ref($0) }
 }