feat(userspace): programs in /bin w/o .elf; bin manifests (needs = display) so shell runs snake; Ctrl+C kills foreground via terminal interrupt notification; ctrl keys; sleep

Makefile

@@ -52,7 +52,7 @@ kani: kani-types kani-domain kani-kernel
 # adapter's build.rs).
 build:
 	cargo build --target $(RISCV_TARGET) --release \
-		-p init -p echo -p snake \
+		-p init -p echo -p sleep -p snake \
 		-p display-qemu -p input-qemu -p storage-qemu \
 		-p log-server -p permission-manager -p session-server -p smptest -p spawntest -p hello \
 		-p terminal-server -p shell -p cat -p ls
@@ -61,7 +61,7 @@ build:
 image: build
 	scripts/make-disk-image.sh
 
-# Boots a test image (normal image + smptest.elf) on $(SMP) harts; init runs
+# Boots a test image (normal image + bin/smptest) on $(SMP) harts; init runs
 # the SMP self-test and halts. Passes only on "SMPTEST PASS".
 test-qemu: build
 	IMG=test.img SMPTEST=1 scripts/make-disk-image.sh > /dev/null