Prevent SRG SSR livestreams from being played in the past

[defagos]

Pull request

Description

This PR ensures that player livestream items delivered by CoreBusiness cannot be played in the past.

Changes made

• Implement short buffering strategy with live edge anchoring.
• Update the demo with an example (Showcase tab).
• Update player item creation API.

Checklist

• Your branch has been rebased onto the main branch.
• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).

[rts-devops]

🌙 Available in TestFlight nightlies

The most recent state can be tested in the following builds:

Platform	Version
iOS	1.0.0 (118)
tvOS	1.0.0 (104)