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
Gabriel Kaszewski
76f10ff1f1