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/types/Cargo.toml

@@ -4,3 +4,6 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ["cfg(kani)"] }