chore(release): prepare 2.2.1

[hatemragab]

Summary

• bump v_video_compressor from 2.2.0 to 2.2.1
• publish the SwiftPM compatibility fix from fix: require iOS 15 for SwiftPM #23 and iOS videoBitrate hardening from iOS: honour videoBitrate via fileLengthLimit #21
• convert the existing Unreleased notes into the dated 2.2.1 changelog entry
• refresh the example Dart and CocoaPods lock metadata

Compatibility and impact

This is a backward-compatible patch release. Default compression behavior remains unchanged unless an explicit iOS videoBitrate is supplied. SwiftPM consumers require iOS 15+, while CocoaPods retains iOS 12+ support as documented.

Validation

• flutter analyze — no issues
• flutter test — 97 passed
• cd example && flutter test test — 3 passed
• isolated VVideoFileLengthBudgetTests — 7 passed
• SwiftPM iOS debug build without codesigning — passed
• CocoaPods iOS debug build without codesigning — passed
• physical iPhone bitrate audit — all 5 mandatory bitrate cases passed
• flutter pub publish --dry-run — 0 warnings, 697 KB archive