Introduce portable SilverScript ABI artifacts

[someone235]

This PR introduces a portable, versioned ABI artifact shared by the compiler, debugger, and external tooling.

There are no intentional SilverScript syntax, bytecode, or runtime-semantics changes. The practical change is that compiled contract metadata and signature-script encoding no longer depend on the compiler’s
internal AST representation.

Artifact and Tooling Changes

• Add SilAbiArtifact, containing:

  • Compiler and schema versions
  • Struct definitions
  • Contracts and runtime-state layouts
  • Entrypoint parameters and dispatch tags
  • Covenant declaration entrypoint metadata
  • Compiled bytecode and script hex
  • Template hashes and state spans

• Add ArtifactValue as the portable representation for constructor and entrypoint arguments.

• Add typed encoders for:

  • Regular entrypoint signature scripts
  • Covenant declaration calls
  • Struct and struct-array arguments
  • Runtime-state scripts

• Add artifact validation for schema versions, dispatch-tag collisions, bytecode encodings, runtime-state spans, and template hashes.

• Preserve compiler-generated dispatch tags in CompiledContract, while moving the complete public ABI representation into SilAbiArtifact.

• Add SilDebugArtifact, which combines a portable ABI artifact with per-contract debug information.

• Migrate the debugger to use portable ABI types for argument parsing, entrypoint selection, signature-script generation, and covenant metadata.

CLI Changes

silverc now emits a SilAbiArtifact JSON document instead of serializing the compiler’s internal CompiledContract.

Constructor argument files now use portable artifact values:

[
  {
    "kind": "bytes",
    "value": [1, 2, 3, 4]
  },
  {
    "kind": "int",
    "value": 12345
  }
]

The generated artifact has the following general shape:

{
  "schema_version": 1,
  "compiler_version": "0.1.0",
  "structs": [],
  "contracts": [
    {
      "name": "Example",
      "runtime_state": {
        "source": "State",
        "fields": []
      },
      "entries": [
        {
          "name": "main",
          "dispatch_tag": "01234567",
          "params": [
            {
              "name": "amount",
              "type": {
                "kind": "int"
              }
            }
          ]
        }
      ],
      "compiled": {
        "bytecode": [],
        "script_hex": "",
        "template_hash": [],
        "template_hash_hex": "",
        "state_span": {
          "offset": 0,
          "len": 0
        }
      }
    }
  ]
}

Programmatic Usage

Contracts can be compiled directly into portable artifacts:

use silverscript_lang::compiler::compile_to_sil_abi_artifact;

let artifact = compile_to_sil_abi_artifact(
    source,
    &[100.into()],
)?;

let contract = artifact.contract("Example").expect("contract exists");

Signature scripts are generated from the portable ABI:

use silverscript_abi::encode_contract_entry_sig_script;

let sigscript = encode_contract_entry_sig_script(
    &artifact,
    "Example",
    "main",
    &[100.into()],
)?;