fix: sched round-robin, cap slot OOB panic, clippy, make ci

- RunList -> intrusive FIFO, no starvation, no silent drop
- cap table sized to CapSlot range (kani caught OOB panic)
- snake food color test uses const
- kani cfg lint, RUST_MIN_STACK for big kernel struct in tests

crates/domain/src/endpoint/mod.rs

@@ -113,15 +113,19 @@ impl EndpointTable {
     }
 
     pub fn remove_thread_from_all(&mut self, thread: ThreadId) {
-        for slot in &mut self.endpoints {
-            if let Some(ep) = slot {
-                ep.remove_sender(thread);
-                ep.remove_receiver(thread);
-            }
+        for ep in self.endpoints.iter_mut().flatten() {
+            ep.remove_sender(thread);
+            ep.remove_receiver(thread);
         }
     }
 }
 
+impl Default for EndpointTable {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 pub trait MessagePassing {
     fn send(
         &mut self,

crates/domain/src/endpoint/wait_queue.rs

@@ -44,3 +44,9 @@ impl WaitQueue {
         self.count == 0
     }
 }
+
+impl Default for WaitQueue {
+    fn default() -> Self {
+        Self::new()
+    }
+}