refactor(models): update data models and remove deprecated IM entities

- Update channel, notification, PR, repo, user, workspace models
- Remove deleted IM models: articles, channel follows, message
  attachments/bookmarks/drafts/edit history/embeds/mentions/pins/
  polls/reactions/threads, saved messages, thread read states
- Add new PR models: review requests, templates
- Add repo release assets model
- Add base_info module for API detail responses

models/channels/channel_permission_overwrites.rs

@@ -1,4 +1,4 @@
-use crate::models::common::{OverwriteTarget, Permission};
+use crate::models::common::OverwriteTarget;
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
@@ -9,8 +9,8 @@ pub struct ChannelPermissionOverwrite {
     pub channel_id: Uuid,
     pub target_type: OverwriteTarget,
     pub target_id: Uuid,
-    pub allow: Vec<Permission>,
-    pub deny: Vec<Permission>,
+    pub allow: Vec<String>,
+    pub deny: Vec<String>,
     pub created_by: Uuid,
     pub created_at: DateTime<Utc>,
     pub updated_at: DateTime<Utc>,