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/kernel/src/syscall/lifecycle.rs

@@ -1,4 +1,3 @@
-use domain::process::MAX_THREADS_PER_PROCESS;
 use platform::Platform;
 
 use super::{SyscallOutcome, SyscallResult};