fix(im): parse Drafty entities for message type classification (#31)

Favorites from Drafty messages (link/file/image/video/voice) always fell back to text because imMessageType only recognized flat file_id/url content. Derive the type from Drafty ent[] entities: LN->link, IM->image, VD->video, AU->voice, EX refined by mime. Attachments win over inline links.

server/im_http.go

@@ -8885,10 +8885,70 @@ func imMessageType(msg *types.Message) string {
 		if stringFromAny(content["url"]) != "" {
 			return "link"
 		}
+		if mtype := draftyIMMessageType(content); mtype != "" {
+			return mtype
+		}
 	}
 	return "text"
 }
 
+// draftyIMMessageType derives the semantic message type from Drafty content
+// ({"txt","fmt","ent"}), where "ent" holds entity definitions {"tp","data"}.
+// Attachment entities win over inline links; EX is refined by its mime type.
+// Returns "" when no recognized entity is present.
+func draftyIMMessageType(content map[string]any) string {
+	ents, ok := content["ent"].([]any)
+	if !ok || len(ents) == 0 {
+		return ""
+	}
+	link := ""
+	file := ""
+	for _, e := range ents {
+		ent, ok := e.(map[string]any)
+		if !ok {
+			continue
+		}
+		data, _ := ent["data"].(map[string]any)
+		switch stringFromAny(ent["tp"]) {
+		case "IM":
+			return "image"
+		case "VD":
+			return "video"
+		case "AU":
+			return "voice"
+		case "EX":
+			if file == "" {
+				file = draftyAttachmentType(data)
+			}
+		case "LN":
+			if link == "" {
+				link = "link"
+			}
+		}
+	}
+	if file != "" {
+		return file
+	}
+	return link
+}
+
+func draftyAttachmentType(data map[string]any) string {
+	mime := ""
+	if data != nil {
+		mime = stringFromAny(data["mime"])
+	}
+	switch {
+	case strings.HasPrefix(mime, "image/"):
+		return "image"
+	case strings.HasPrefix(mime, "video/"):
+		return "video"
+	case strings.HasPrefix(mime, "audio/"):
+		return "voice"
+	default:
+		return "file"
+	}
+}
+
 func favoriteSnapshot(msg *types.Message) map[string]any {
 	if msg == nil {
 		return map[string]any{}