create `builds/` dir with `target_*b` dirs and update artifact/release CI

[Autoparallel]

Mission

We currently have our release artifacts created by building the files of the form circuits/*.circom. This isn't really sustainable. I will outline my thoughts for this below.

Tasks

• [ ] Let's instead create a new directory for the specific purpose of housing main components of circuit builds that interface with one another. I propose the following organization:

  builds/
  ---- target_1024b/
  -------- aes_gcm_nivc_1024b.circom
  -------- json_parse_nivc_1024b.circom
  -------- ...
  ---- target_2048b/
  -------- aes_gcm_nivc_2048b.circom
  -------- json_parse_nivc_2048b.circom
  -------- ...
  ---- target_*b/

  Basically, this allows us to set up a collection of different builds that target specific max plaintext size. Let's start perhaps just with 512b, 1024b, and 2048b.

• [ ] The *_nivc_*b.circom files should adopt this (or similar) semantic naming scheme.
• [ ] The *_nivc_*b.circom files should solely be a main component.
• [ ] OPTIONALLY: We could deploy these different sizes with the CI itself and not have these *_nivc_*b.circom files in here at all. Though I think this is just more challenging than we need at the moment.

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We will have to pick MAX_* sizes for other parameters too. Let's start with reasonable values that will work in many cases and we can always change later. I'll let the assignee decide these sizes.