Disco! 3.4.1

Music Assistant over Sendspin 1.0

MA Sendspin now speaks the current Sendspin standard (experimental). It needs Music Assistant 2.10.7 or newer;
older servers get a clear "Needs Music Assistant 2.10.7 or newer" on the Sendspin screen.

• End-to-end encrypted. Every connection to Music Assistant runs inside a Noise channel (KKpsk2), with keys made
  on the Disc and kept in /usr/data/diskos-sendspin.keys. The cryptography is Monocypher 4.0.2.
• Pairing with a code. Pair the Disc from Music Assistant: the Disc wakes and shows a 6-digit code (or a QR code)
  over everything; type it in. A wrong code can be tried again; Cancel ends it. Or pair without a code: scan
  Settings › MA Sendspin › Pairing Token in Music Assistant (keep that QR private).
• Allow Unpaired (on by default): Music Assistant can play once you approve the Disc there. Off: only paired
  servers can play. Forget Servers removes every pairing.
• Album artwork from Music Assistant in Music, at 360 × 360.
• FLAC first (lossless, about half the Wi-Fi traffic), PCM still offered.
• Sync Delay moves in 10 ms steps, with − / + buttons; double-tap the slider for 0.
• Music Assistant's volume follows the Sendspin curve.

Squash and Disco

• New Bluetooth and Wi-Fi screens. One row on top: refresh, the icon on a disc, a small switch in the theme's
  accent. The icon's shade says it: grey when off, the theme's ink when on. A ring round it spins while it turns on or
  scans, with a big "Scanning…" in the middle; on Wi-Fi it fills with the signal while connected. Taller rows with a
  larger status line ("Connected – LDAC", "Connected – 192.168.1.42"), and everything stays inside the circle.
• Disco Quick Settings: the bubbles sit on an oval, the left pair out by the rim, Wi-Fi with room around it.

Everywhere

• A real AirPlay icon instead of the Wi-Fi fan, in Working mode and the Quick Settings Mode toggle; Working mode
  uses the same icons in every theme (Zune stays text-only).
• Sendspin on the Zune home dial, after "modes".

Fixed

• Up Next froze the Disc on a large shuffled queue. It read and numbered the whole queue at once; on a
  28,619-song shuffle that took the Disc down when Up Next opened (or when the menu stepped over it). It now reads only
  the songs it shows.
• Previous on shuffle played some other song. Disco now remembers the last 50 songs that played: on shuffle,
  Previous goes back to them, and Next retraces them before shuffling on. (A jump makes FiiO's player reshuffle the
  songs you haven't heard yet.) The volume keys still use the player's own Previous.

For developers

• A stall reporter: if the interface ever stops responding for 3 seconds, /usr/data/diskos_crash.log gets a STALL
  line with the screen and the last thing it was asked to do, while it is still stuck.
• Host tests: ui/tests/sendspin_crypto_test.c, ui/tests/sendspin_interop_test.py (against aiosendspin, the library
  Music Assistant uses), ui/tests/shufhist_test.c.

Binary record: RELEASE_3.4.1.md. Update from the SD card as usual
(guide); no reflash.