feat(kernel): seL4-style IPC, notifications, status ABI

- badges + Mint, Call/Reply/ReplyRecv w/ gen-checked reply slot
- cap transfer (1/msg, copy, needs Delegate, rechecked at delivery)
- notifications: signal/wait/poll/bind, irq -> notification routing
- WaitAny/WaitForInterrupt removed; a0=status, ErrorCode
- libkos: single ecall primitive, compat wrappers + typed new api
- fix: trap return clobbered user t0 on every trap
- fix: wait queues FIFO, delegate keeps badge, fault cap checked
- docs/ipc.md spec, ipc tests, ipc fuzz, kani ntfn + waitqueue

crates/kernel/src/tests/helpers.rs

@@ -5,7 +5,7 @@ use platform::Platform;
 use types::{
     address::PhysicalAddress,
     bounded::{CapSlot, Priority},
-    id::{EndpointId, IrqId, ProcessId, ThreadId},
+    id::{EndpointId, ProcessId, ThreadId},
     permission::PermissionSet,
     time::TimeSlice,
 };
@@ -41,10 +41,6 @@ impl Kernel<MockPlatform> {
         tid
     }
 
-    pub fn register_irq_for_test(&mut self, irq: IrqId, thread: ThreadId) {
-        let _ = self.irqs.register(irq, thread);
-    }
-
     pub fn block_thread_for_test(&mut self, tid: ThreadId, reason: domain::thread::BlockReason) {
         let core = self.platform.core_id();
         if let Ok(t) = self.threads.get_mut(tid) {
@@ -128,6 +124,10 @@ impl Kernel<MockPlatform> {
         }
     }
 
+    pub fn destroy_process_notifications_for_test(&mut self, owner: ProcessId) {
+        self.destroy_notifications_owned_by(owner);
+    }
+
     pub fn thread_state_for_test(&self, tid: ThreadId) -> Option<ThreadState> {
         self.threads.get(tid).ok().map(|t| *t.state())
     }