SDK hardening: Jest tests + Android requestTrackingAuthorization semantics

[ahsanalidotme]

Part of the React Native checklist for linktrail-backend#114.

Covered

• RN had no tests: added Jest (react-native preset, inline babel-jest config so the bob build is unaffected), 26 tests in __tests__/index.test.ts over the JS/TS layer with a mocked native module: API surface, argument passing, configure/deep-link forwarding (Linking initial + events, autoHandleLinks), onLink/onAttribution/onError emitters, error propagation, platform behavior of the paste button. npm test script added.
• Android requestTrackingAuthorization now resolves true (was false), matching Flutter. Android has no ATT, so the platform never restricts tracking; app-level consent remains setConsent/requireConsent. Documented in JSDoc, the codegen spec, README and CHANGELOG (Unreleased, flagged as a behavior change). iOS unchanged.

Not covered

• CI: ci.yml has no npm test step. Workflow edits are intentionally not in this PR (pushes touching .github/workflows are rejected); a one-step patch is provided separately.
• Native Kotlin/Swift behavior is not exercised by these tests (the Android change is a one-line native edit, not built or run here).
• Other issue items (Flutter, offline queue, TLS pinning, PLAN/ROADMAP) belong to other repos.

Closes linktrail-io/linktrail-backend#114

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