Implement domain and endpoint modules with capability management, message passing, and scheduling features

crates/domain/src/error.rs

@@ -0,0 +1,11 @@
+use types::{bounded::CapSlot, id::ProcessId, permission::Permission};
+
+#[derive(Debug)]
+pub enum KernelError {
+    InvalidSlot(CapSlot),
+    RevokedCapability(CapSlot),
+    PermissionDenied { slot: CapSlot, needed: Permission },
+    NoFreeSlot,
+    InvalidProcess(ProcessId),
+    WouldBlock,
+}