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/scheduler/multi_core.rs

@@ -38,6 +38,14 @@ impl MultiCoreScheduler {
         self.cores[core.raw() as usize].set_current(thread);
     }
 
+    /// Runs `thread` next on `core` regardless of its place in the queue.
+    /// Fails if it is not queued there.
+    pub fn run_now(&mut self, core: CoreId, thread: ThreadId) -> bool {
+        self.cores
+            .get_mut(core.raw() as usize)
+            .is_some_and(|c| c.run_now(thread))
+    }
+
     fn thread_count_on(&self, core: CoreId) -> usize {
         self.placements
             .iter()