feat: snooze command with basic ID support

test/snooze.bats

@@ -0,0 +1,28 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+@test "snooze by ID creates entry in snoozed file" {
+  run_nag at "tomorrow 3pm" "take a break"
+  run_nag snooze 1
+  [ "${status}" -eq 0 ]
+  [[ "${output}" =~ "Snoozed [1]" ]]
+  [ -f "${NAG_DIR}/snoozed" ]
+  grep -q "^1$" "${NAG_DIR}/snoozed"
+}
+
+@test "snooze by ID shows alarm message in output" {
+  run_nag at "tomorrow 3pm" "take a break"
+  run_nag snooze 1
+  [[ "${output}" =~ "take a break" ]]
+}
+
+@test "snooze with nonexistent ID fails" {
+  run_nag snooze 99
+  [ "${status}" -eq 1 ]
+}
+
+@test "snooze with no args fails" {
+  run_nag snooze
+  [ "${status}" -eq 1 ]
+}