First release.

• Lifetime hours per physical pair of headphones, with generations so a replacement pair starts at zero instead of inheriting the old one's total.
• Every connection kept permanently, with per-day and per-pair statistics.
• Optional detailed tracking for wired and USB headphones, and for playback versus connected time.
• Cost per listening hour.
• JSON export and import.
• No internet permission: no accounts, no analytics, no tracking.
