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/scheduler/per_core.rs

@@ -29,12 +29,12 @@ impl PerCoreScheduler {
         self.queue.add(thread, priority);
     }
 
-    pub fn remove(&mut self, thread: ThreadId, priority: Priority) {
-        self.queue.remove(thread, priority);
+    pub fn remove(&mut self, thread: ThreadId) {
+        self.queue.remove(thread);
     }
 
     pub fn pick_next(&mut self) -> Option<ThreadId> {
-        let (thread, _priority) = self.queue.next()?;
+        let (thread, _priority) = self.queue.pop_highest()?;
         self.current = Some(thread);
         Some(thread)
     }
@@ -56,6 +56,10 @@ impl PerCoreScheduler {
     }
 
     pub fn len(&self) -> usize {
-        self.queue.bitmap().count_ones() as usize
+        self.queue.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.queue.is_empty()
     }
 }