test: add Jest config, unit tests, and CI workflow

[mCodex]

• Add jest.config.js and tsconfig.test.json for test environment
• Add comprehensive unit tests and mocks under src/tests
• Add GitHub Actions workflow .github/workflows/test.yml to run tests
• Add test scripts and devDependencies (jest, ts-jest, jest-environment-jsdom, @testing-library, ts-node, react-dom) and update yarn.lock
• Move coverage badge & add React Native minimum to README; minor .gitignore newline fix

[Copilot]

Pull Request Overview

This PR introduces a comprehensive testing infrastructure for the react-native-sensitive-info library, including Jest configuration, unit tests for core functionality and React hooks, mocking utilities, and a GitHub Actions CI workflow to run tests automatically.

Key Changes

• Added Jest testing infrastructure with TypeScript support (jest.config.js, tsconfig.test.json)
• Created comprehensive unit tests covering storage operations, hooks, internal utilities, and error handling
• Implemented GitHub Actions workflow to run tests on push/PR with coverage reporting

Reviewed Changes

Copilot reviewed 22 out of 25 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tsconfig.test.json	TypeScript configuration for test environment with CommonJS module support
src/tests/storage.test.ts	Unit tests for core storage API functions with mocked native layer
src/tests/internal.options.test.ts	Tests for options normalization and default value handling
src/tests/internal.native.test.ts	Tests verifying native instance memoization behavior
src/tests/internal.errors.test.ts	Tests for error detection and message extraction utilities
src/tests/index.test.ts	Tests ensuring package entrypoint exports are correct
src/tests/hooks.useStableOptions.test.tsx	Tests for options memoization hook behavior
src/tests/hooks.useSecurityAvailability.test.tsx	Tests for security capabilities detection hook
src/tests/hooks.useSecureStorage.test.tsx	Comprehensive tests for secure storage hook operations
src/tests/hooks.useSecureOperation.test.tsx	Tests for async operation wrapper hook
src/tests/hooks.useSecretItem.test.tsx	Tests for individual secret item management hook
src/tests/hooks.useSecret.test.tsx	Tests for secret CRUD operations hook
src/tests/hooks.useHasSecret.test.tsx	Tests for secret existence checking hook
src/tests/hooks.useAsyncLifecycle.test.tsx	Tests for async lifecycle management utilities
src/tests/hooks.types.test.ts	Tests for hook error types and state initializers
src/tests/hooks.error-utils.test.ts	Tests for hook error creation utility
src/tests/core.storage.test.ts	Detailed tests for storage layer with native delegation
src/tests/mocks/react-native.ts	Mock implementation of React Native core modules
src/tests/mocks/react-native-nitro-modules.ts	Mock implementation of Nitro Modules hybrid objects
package.json	Added test scripts and testing dependencies (Jest, Testing Library, ts-jest)
README.md	Added coverage badge and React Native minimum version requirement
.github/workflows/test.yml	CI workflow configuration for running tests on push/PR

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