feat: add announcement channels, publishing and following (#3090)

packages/schema/proto/fluxer/user/preferences/v1/preferences.proto

@@ -51,6 +51,7 @@ message SyncedPreferences {
   optional bool save_camera_uploads_to_device = 113;
   ReactionEmoji double_tap_reaction = 114;
   ChannelFrecencyState channel_frecency = 115;
+  AnnouncementPromptsState announcement_prompts = 116;
 
 }
 
@@ -222,6 +223,10 @@ message VoicePromptsState {
   bool skip_hide_own_screenshare_confirm = 2;
 }
 
+message AnnouncementPromptsState {
+  bool hide_publish_nudge = 1;
+}
+
 message SudoPromptState {
   optional MfaMethod last_used_mfa_method = 1;
 }