Revamp README: Swift facade, install & metadata

Rewrites the README to modernize documentation and emphasize the new Swift-first facade. Adds a products table, updated installation instructions for Swift Package Manager, CocoaPods, and Carthage, plus examples for Swift and Objective-C (parsing, formatting, as-you-type, short numbers, geocoding). Removes old badges and legacy instructions, and adds maintenance/metadata update workflow, testing commands, and a release checklist to help contributors keep upstream parity with Google's libphonenumber.

Author: iziz