Add buffer integration test

Rearrange channel crate structure
Get channel buffer from database

co-authored-by: Max <max@zed.dev>

crates/client/src/user.rs

@@ -10,9 +10,11 @@ use std::sync::{Arc, Weak};
 use util::http::HttpClient;
 use util::TryFutureExt as _;
 
+pub type UserId = u64;
+
 #[derive(Default, Debug)]
 pub struct User {
-    pub id: u64,
+    pub id: UserId,
     pub github_login: String,
     pub avatar: Option<Arc<ImageData>>,
 }