N-OS update: fixing saves, video and music

Player reports exposed a connected set of N-OS failures: stage ten could stay locked after the required ICU and forum actions, videos failed on clean user PCs, scrubbing froze, music showed 0:00 or Out of memory, and localized buttons were clipped.

I reproduced the issues with migrated saves, exact 17-byte CRLF media links and the frozen Windows build. The toolkit: Python, pytest, headless pygame QA, OpenCV, FFmpeg and FFprobe, PyInstaller, SteamCMD and SteamPipe.

The fix migrated stale story flags, bundled CV2 and FFmpeg, resolved old media links, cached video frames and audio, repaired music duration caching and measured translated UI labels across 13 languages.

Proof: 452 tests and 298 subtests passed. OpenCV decoded frames from all 17 registered videos, FFprobe checked every file, bundled FFmpeg extracted audio, and the Windows game plus DLC were uploaded to SteamPipe.