chore: rename package to react-native-share-content

[ngocdevv]

Summary

• rename the npm package and public brand from expo-share-content to react-native-share-content
• bump the new package line to 0.2.0 and update package/lockfile metadata
• migrate the example app, installation/import snippets, docs, npm links, GitHub links, and GitHub Pages base path
• update CocoaPods source metadata and npm Trusted Publishing documentation
• keep the JavaScript API, native module names, Android namespace, and legacy expo-share-content-intent generated-code marker unchanged for upgrade compatibility
• add README and changelog migration guidance for existing users

External configuration completed

• GitHub repository renamed to ngocdevv/react-native-share-content
• repository homepage changed to https://ngocdevv.github.io/react-native-share-content/
• local origin changed to git@github.com:ngocdevv/react-native-share-content.git
• legacy GitHub repository URL verified to redirect with HTTP 301

Verification

• npm test: 7 suites, 40/40 tests pass
• npm run lint: pass with zero warnings
• npm run build:all: pass
• npm run verify:cjs: pass
• generated-output diff check: pass
• cd docs && npm run typecheck: pass
• cd docs && npm run build: pass
• npm pack: react-native-share-content-0.2.0.tgz, 53 entries
• packed manifest verified as react-native-share-content@0.2.0
• tarball install smoke test resolved react-native-share-content/app.plugin.js
• tarball SHA-256: 9f2e07f2ec57e6ff7c44484fef8690facc794aca1f0ecde54866f1afa1f5009e

Release migration

react-native-share-content must be bootstrapped once with an interactive npm publish because npm requires a package to exist before a Trusted Publisher can be configured. After the first publish, bind publish-npm.yml to the new npm package, merge this PR, verify Pages/registry/CI, then deprecate expo-share-content with a migration message.