Fix media progress resetting when the notch opens

[xand0dev]

Summary

• include MediaRemote's playback timestamp in helper snapshots
• project the reported elapsed position to the current time before updating the scrubber
• preserve paused positions and guard against future timestamps
• add three regression tests and document the fix

Root cause

MediaRemote's elapsed value belongs to the last system update rather than the instant VoidBar reads it. Opening the notch triggers a manual refresh, so the old value was interpreted as a real backward seek and reset the progress bar.

Validation

• swift test — 5 tests passed
• ./Scripts/bundle.sh release — succeeded, including the Objective-C helper
• git diff --check