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/thread/mod.rs

@@ -20,6 +20,7 @@ pub struct Thread {
     core_affinity: Option<CoreId>,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum ThreadState {
     Ready,
     Running(CoreId),
@@ -77,6 +78,7 @@ impl SavedContext {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum BlockReason {
     Sending(CapSlot),
     Receiving(CapSlot),