Recover failed iPad PiP display layers

[alantangok]

Summary

• flush and rebuild the cached format only when the display layer reports recoverable decoder starvation through requiresFlushToResumeDecoding
• mark only the first successfully created post-recovery frame for immediate display
• treat other failed-layer states as terminal: log the status/error once and stop or fail PiP cleanly without a repeated flush loop
• keep the existing GL capture/enqueue path unchanged and avoid a broader display-layer/controller rebuild

Verification

• unsigned Release iOS device build succeeded
• Xcode Release static analysis succeeded
• temporary state-machine checks cover steady, recoverable, and terminal failure paths; the pre-fix terminal flush loop was reproduced before the change
• no project file, .checkpoint, or scripts/ changes

Device validation still required

• repeated PiP/background/foreground and stream-resolution changes to exercise decoder-starvation recovery
• terminal failure fault injection: confirm one log, one stop/failure callback, and no repeated flush loop
• repeat PiP start/stop after terminal failure and confirm graceful rejection until teardown/setup
• test iOS 15–17 and iOS 18+; migration to sampleBufferRenderer is intentionally out of scope

Split from #93.

[SandiyosDev]

This one I can take

before I merge, the flush branch needs a cap so a decoder that stays starved doesn't flush on every frame forever, the NSLog should go through sdkLog like the rest of the app, and displayImmediatelyAfterRecovery is written from both threads outside the lock you added

[SandiyosDev]

What was your repro for the black PiP?