Breach 0.2.3 (super admins)

Prototype build for super-admin accounts only; hidden from and refused to everyone else server-side.

• Caustic scope (Ben, #353): the band becomes water seen from a low camera, with a real caustic on its floor driven by level, cutoff, notes, timbre and the mod wheel. In this build it is on only when launched with BREACH_SCOPE=caustics (the admin switch arrives in the next build). CPU reference implementation (~1 s per frame), not the shipping 60 fps path.
• Brine (Deep) is the default column (Ben, #353).
• Light ghost on the golden face (Ben, #347).
• Arp: turning Arp on with keys held, Latch off, or Arp off/on no longer leaves stuck notes or a phantom pattern (#356).
• Engine swaps keep held notes and fade instead of clicking; Sync sways no longer rebuild every block (#355).