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/Cargo.toml

@@ -5,3 +5,6 @@ edition = "2024"
 
 [dependencies]
 types = { workspace = true }
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ["cfg(kani)"] }