Add latch SMV example to Spec Mutation

[skhuang]

Summary

• add a cross-coupled latch NuSMV source example to the SMV/model-checking examples
• expose it as predicate !(x && y) for Specification Mutation
• update lecture Show path optimization metrics in graph coverage UI #8 slide text from 7 to 8 SMV examples and regenerate decks/standalone
• add unit and browser coverage for selecting the new example

Tests

• npm run build:slide-decks
• npm run build:standalone
• npm test -- --run src/tests/specMutation.test.js
• npm test -- --run
• npx playwright test e2e/spec-mutation.spec.js --project=chromium