Relaunch ViewMonitor with a SwiftUI demo and modern README

[daisuke0131]

Summary

• reposition ViewMonitor as an in-app visual layout inspector for UIKit and SwiftUI
• add a real Simulator-recorded SwiftUI demo GIF showing two-element gap measurement
• add an opt-in XCUITest choreography and reproducible MP4-to-GIF capture tooling
• document installation, capabilities, relationship measurements, measurement behavior, and SwiftUI limitations

Why

ViewMonitor already supports modern Swift 6, SwiftUI inspection, and two-view relationship measurements, but the repository front page did not communicate those capabilities quickly. This prepares the project for a 2.x relaunch with a clearer value proposition and a reusable, authentic product demo.

Impact

The README now shows the primary workflow immediately and gives both SwiftUI and UIKit users a concise setup path. The capture test is compile-gated and skipped in ordinary test runs, so normal CI behavior remains unchanged. No production library source or package manifest is modified.

Validation

• ViewMonitor package: 128 tests passed
• SwiftUI Example UI tests: 5 passed, 1 capture-only test skipped
• UIKit Example UI tests: 2 passed
• SwiftLint strict: 0 violations across 51 files
• capture shell script syntax/help verified
• GIF converter compile/help/error handling verified
• README local links verified
• generated GIF verified at 360×779 and 139,062 bytes
• git diff --check passed