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/irq/mod.rs

@@ -36,3 +36,9 @@ impl IrqRoutingTable {
         self.owners[irq.raw() as usize]
     }
 }
+
+impl Default for IrqRoutingTable {
+    fn default() -> Self {
+        Self::new()
+    }
+}