Use the t tag for hashtags

Changelog-Changed: #hashtags now use the `t` tag instead of `hashtag`
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Models/Mentions.swift

@@ -264,7 +264,7 @@ func make_post_tags(post_blocks: [PostBlock], tags: [[String]]) -> PostTags {
                 blocks.append(block)
             }
         case .hashtag(let hashtag):
-            new_tags.append(["hashtag", hashtag.lowercased()])
+            new_tags.append(["t", hashtag.lowercased()])
             blocks.append(.hashtag(hashtag))
         case .text(let txt):
             blocks.append(Block.text(txt))

damus/Nostr/NostrFilter.swift

@@ -23,7 +23,7 @@ struct NostrFilter: Codable {
         case kinds
         case referenced_ids = "#e"
         case pubkeys = "#p"
-        case hashtag = "#hashtag"
+        case hashtag = "#t"
         case since
         case until
         case authors

damus/Views/NoteContentView.swift

@@ -63,7 +63,7 @@ struct NoteContentView: View {
 }
 
 func hashtag_str(_ htag: String) -> String {
-    return "[#\(htag)](nostr:hashtag:\(htag))"
+    return "[#\(htag)](nostr:t:\(htag))"
 }
 
 func mention_str(_ m: Mention, profiles: Profiles) -> String {

damus/Views/ThreadView.swift

@@ -80,6 +80,7 @@ func should_show_chatroom(_ ev: NostrEvent) -> Bool {
 }
 
 func tag_is_hashtag(_ tag: [String]) -> Bool {
+    // "hashtag" is deprecated, will remove in the future
     return tag.count >= 2 && (tag[0] == "hashtag" || tag[0] == "t")
 }
 

damusTests/damusTests.swift

@@ -79,9 +79,9 @@ class damusTests: XCTestCase {
         
         XCTAssertEqual(ev.tags.count, 2)
         XCTAssertEqual(ev.content, "#damus some content #bitcoin derp")
-        XCTAssertEqual(ev.tags[0][0], "hashtag")
+        XCTAssertEqual(ev.tags[0][0], "t")
         XCTAssertEqual(ev.tags[0][1], "damus")
-        XCTAssertEqual(ev.tags[1][0], "hashtag")
+        XCTAssertEqual(ev.tags[1][0], "t")
         XCTAssertEqual(ev.tags[1][1], "bitcoin")
         
     }