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/adapter-riscv/src/trap/mod.rs

@@ -251,6 +251,10 @@ fn decode_syscall(frame: &TrapFrame) -> Option<domain::syscall::Syscall> {
             })
         }
         SYS_CREATE_ENDPOINT => Some(Syscall::CreateEndpoint),
+        SYS_DROP_CAP => {
+            let slot = types::bounded::CapSlot::new(a0 as u8)?;
+            Some(Syscall::DropCap { slot })
+        }
         SYS_DEBUG_PUTCHAR => Some(Syscall::DebugPutchar { byte: a0 as u8 }),
         SYS_MAP_PAGE => {
             let slot = types::bounded::CapSlot::new(a0 as u8)?;