Added Multi-Selection to Media and Document Pickers

[fhasse95]

This PR adds multi-selection support to media and document pickers to SkipKit. This is achieved by expanding the existing media and document pickers on Android and by using the PHPickerViewController on iOS, which supports multi-selection.

For more information, check out the updated ReadMe file.

A complete example is also available in the BiometricAuthenticationPlayground of the Skip Showcase app:

iOS:

Android:

Related PR:

• Added Multi-Selection to Media and Document Pickers skipapp-showcase#117

---

Thank you for contributing to the Skip project! Please use this space to describe your change and add any labels (bug, enhancement, documentation, etc.) to help categorize your contribution.

Please review the contribution guide at https://skip.dev/docs/contributing/ for advice and guidance on making high-quality PRs.

Skip Pull Request Checklist:

• REQUIRED: I have signed the Contributor Agreement
• REQUIRED: I have tested my change locally with swift test
• OPTIONAL: I have tested my change on an iOS simulator or device
• OPTIONAL: I have tested my change on an Android emulator or device

---

• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes.

The initial implementation was generated with assistance from Codex. The resulting code was manually reviewed, refined where necessary, and validated using both the Skip Showcase app and my own app on iOS, iPadOS, macOS (Catalyst), and Android to ensure correctness and consistent cross-platform behavior.

---