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

Makefile

@@ -1,10 +1,24 @@
-.PHONY: check fmt clippy test kani build all image run
+.PHONY: check fmt clippy test kani build all image run ci kernel-fmt kernel-clippy kernel-test
 
 RISCV_TARGET = riscv64gc-unknown-none-elf
 KERNEL_BIN = target/$(RISCV_TARGET)/release/adapter-riscv
 
+KERNEL_CRATES = -p types -p domain -p kernel -p platform
+
 all: check fmt clippy test
 
+# Gate for kernel work: formatting, lints, unit tests, Kani proofs, RISC-V build.
+ci: kernel-fmt kernel-clippy kernel-test kani build
+
+kernel-fmt:
+	cargo fmt $(KERNEL_CRATES) -p adapter-riscv -- --check
+
+kernel-clippy:
+	cargo clippy $(KERNEL_CRATES) --all-targets -- -D warnings
+
+kernel-test:
+	cargo test $(KERNEL_CRATES)
+
 check:
 	cargo check --workspace