feat(kernel): object lifetimes via slot generations

- SlotGenerations per table, never wraps, retires exhausted slots
- caps to dead/reused process, endpoint, region rejected
- endpoints owned, die w/ owner, waiters woken w/ error
- DropCap syscall + libkos wrapper
- irq table bounds-checked, routes dropped w/ thread
- self-kill terminates caller, exit_thread full cleanup
- sched run_now: switch to named thread, not queue head
- lifetime tests, fuzz kills/recreates, kani gen proofs

crates/domain/src/lib.rs

@@ -7,6 +7,7 @@ pub mod capability;
 pub mod endpoint;
 pub mod error;
 pub mod fault;
+pub mod generations;
 pub mod irq;
 pub mod memory;
 pub mod message;