users: store timezone, default is "UTC"

crates/users/src/database.rs

@@ -22,6 +22,7 @@ impl From<DatabaseUsers> for User {
             password_recover: db.password_recover,
             paper_key: db.paper_key,
             is_archived: db.is_archived,
+            timezone: db.timezone,
         }
     }
 }
@@ -179,4 +180,14 @@ impl User {
 
         Ok(())
     }
+
+    pub async fn set_timezone(
+        &self,
+        conn: impl SqliteExecutor<'_>,
+        timezone: &str,
+    ) -> Result<(), Error> {
+        DatabaseUsers::set_timezone(conn, self.id.as_ref(), timezone).await?;
+
+        Ok(())
+    }
 }