fix: Ship compiled test mock entry point (fix TS under RN 0.87)

[huntie]

Details

Minimal fix for @expensify/react-native-live-markdown compatibility in React Native 0.87+ projects that wire up the test mock from a TypeScript setup file. See react-native-community/template#245.

Context

React Native 0.87 ships the Strict TypeScript API by default (moving to a user opt-out).

Typically, this change is scoped to the user's project (@react-native/typescript-config includes skipLibCheck: true) and does not reach library source code.

However, this library ships a Jest mock at @expensify/react-native-live-markdown/mock, which is an exception that crosses this boundary.

Problem

@expensify/react-native-live-markdown/mock resolved to raw mock/index.ts — no sibling .d.ts existed at that path — so it pulled this library's ../src/* into the scope of the user's TypeScript analysis instead of the compiled lib/ code. That produces a type error against deep imports such as react-native/Libraries/Types/CodegenTypes, which no longer resolve under the Strict TypeScript API (TS2307, see also AppAndFlow/react-native-safe-area-context#744). skipLibCheck does not contain it because it does not apply to .ts/.tsx.

This diff

Move the mock into the builder-bob build so consuming projects only ever see this library's .d.ts files, which are exempt from typechecking. Same fix as AppAndFlow/react-native-safe-area-context#745, independent of the deep-import cleanup in #744.

• Move mock/index.ts to src/mock/index.ts so builder-bob compiles it like the rest of the library; repoint its imports from '../src' to '..'.
• Preserve the @expensify/react-native-live-markdown/mock subpath via shims: mock/index.js re-exports ../lib/commonjs/mock/index.js, mock/index.d.ts re-exports ../lib/typescript/src/mock/index.
• Drop mock/**/* from tsconfig include so the source is only picked up under src/, and lint-ignore mock/**/* since the shims point into build output.
• ✅ Consuming projects now only see this library's .d.ts files, which are exempt from typechecking due to skipLibCheck: true.

No exports map is introduced — the package has none today, and shims are the conservative, non-breaking equivalent.

Related Issues

• react-native-safe-area-context/jest/mock incompat with RN 0.87 react-native-community/template#245

Manual Tests

• yarn typecheck, yarn lint:root, and the Jest suite (153 tests) all pass.
• yarn prepare (bob build) emits lib/commonjs/mock/index.js, lib/module/mock/index.js, and lib/typescript/src/mock/index.d.ts; the stale lib/typescript/mock/ is gone.
• npm pack --dry-run confirms the three lib/**/mock outputs plus the mock/index.js / mock/index.d.ts shims ship, and mock/index.ts no longer appears at the public mock/ path.
• Verified the emitted lib/commonjs/mock/index.js retains the module-scope global.jsi_* assignments and the 'worklet' directive.

Linked PRs

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[huntie]

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[huntie]

Shims prevent this from being a breaking change. Also achievable by introducing a package.json "exports" field.