Parse a node-particle graph source object (the inner nodeParticle payload) into a ParticleGraph.
The serialized shape mirrors Babylon.js NodeParticleSystemSet.serialize: a flat blocks array where
each block carries customType, id, name, and an inputs array whose entries reference their source
via targetBlockId + targetConnectionName. SystemBlock instances are the graph roots.
Parse a node-particle graph source object (the inner
nodeParticlepayload) into a ParticleGraph.The serialized shape mirrors Babylon.js
NodeParticleSystemSet.serialize: a flatblocksarray where each block carriescustomType,id,name, and aninputsarray whose entries reference their source viatargetBlockId+targetConnectionName.SystemBlockinstances are the graph roots.