feat: Message pinning

crates/core/result/src/lib.rs

@@ -90,6 +90,8 @@ pub enum ErrorType {
     },
     AlreadyInGroup,
     NotInGroup,
+    AlreadyPinned,
+    NotPinned,
 
     // ? Server related errors
     UnknownServer,

crates/core/result/src/rocket.rs

@@ -40,6 +40,8 @@ impl<'r> Responder<'r, 'static> for Error {
             ErrorType::GroupTooLarge { .. } => Status::Forbidden,
             ErrorType::AlreadyInGroup => Status::Conflict,
             ErrorType::NotInGroup => Status::NotFound,
+            ErrorType::AlreadyPinned => Status::BadRequest,
+            ErrorType::NotPinned => Status::BadRequest,
 
             ErrorType::UnknownServer => Status::NotFound,
             ErrorType::InvalidRole => Status::NotFound,