Registers a named ParticleBackend in the BackendManager + barrel in place of
the inline particles PassthroughBackend. Transport is a no-op (the flow-field
canvas reads engine outputs directly via rAF); selecting it gates synth audio
(setMuted) like the other non-synth backends and reports a clear ready status.
Adds the Manifold app (manifold/) — the convertible-mode React front-end on
the real NISPS ML+audio engine, served live at meml.lnfinitemonkeys.org/next/.
Console chrome trimmed per UI pass:
- drop mode label + subtitle from the top-left overlay (keep MEMLNaut wordmark)
- remove the composite split preset/ratio readout (top-centre)
- remove the OUTPUT corner tag above the bars
- remove the A/B compare toggle from the verdict cluster
- remove the follow button + input/noise readout (bottom-left)
- remove AltitudeNav focus switcher (bottom-right)
