[giolaq]

Fix starter tooling so type checks, tests, and lint run
Several validation commands failed on a fresh clone before any workshop
changes, which also blocks the Step 7 prompt's validation list:

• shared: tsconfig used moduleResolution "bundler", which TypeScript 4.9
  rejects; switch to "node" and map @amazon-devices/* and
  lottie-react-native to the Vega workspace.
• shared: the @testing-library/react-native Jest preset no longer exists;
  use the Vega workspace's React Native preset and module paths, and
  enable RNTL's built-in matchers.
• vega: shared files couldn't resolve react-native/react during ts-jest
  type checks or at runtime; add tsconfig paths and Jest modulePaths.
• vega: replace the stale template test (it looked for a "sampleLink"
  testID that doesn't exist) with a render test of the home tiles.
• expotv: add eslint and eslint-config-expo so yarn lint runs.
• expotv: add yarn typecheck with tsconfig.typecheck.json. It keeps the
  React type mappings out of tsconfig.json (which Expo Metro reads) and
  includes Expo's types, since expo-env.d.ts only exists after
  expo start.