Hangs/regressions fail fast instead of stalling CI.
- shared/jest.config.js: testTimeout 10000
- src/setupTests.js: jest.setTimeout(10000) (CRA blocks testTimeout in
package.json — not in allowlist)
- server/jest.config.js: already had 10000
Verified: injected hanging test -> 'Exceeded timeout of 10000 ms'.