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/capability/mod.rs

@@ -8,7 +8,8 @@ use crate::{error::KernelError, resource::Resource};
 #[path = "tests.rs"]
 mod tests;
 
-const MAX_CAPS_PER_PROCESS: usize = 16;
+// Sized so that every representable `CapSlot` indexes a real slot.
+pub const MAX_CAPS_PER_PROCESS: usize = CapSlot::MAX as usize + 1;
 
 pub struct Capability {
     resource: Resource,
@@ -76,3 +77,9 @@ impl CapabilityTable {
         Ok(())
     }
 }
+
+impl Default for CapabilityTable {
+    fn default() -> Self {
+        Self::new()
+    }
+}