Refactor CallStack::Synthesize to produce consistent dummy outputs for faster nested import deployments

[kpandl]

Summary

This PR refactors the way CallStack::Synthesize is run, decoupling the Synthesize mode from the old execute_function approach. It produces consistent dummy outputs (inspired by CheckDeployment) more rapidly and skips sub-circuit construction for nested import calls. The result is significantly faster deployments for deeply nested imports, while still generating cryptographically coherent record nonces.

Motivation

Previously, Authorize and Synthesize modes were lumped together. As such, calls in CallStack::Synthesize were forced to run a real sub-circuit via execute_function. This is slow for nested imports and has led to an exponential growth in deployment time w.r.t. the import depth.

Thus, this PR refactors the Synthesize branch to skip full circuit execution and produce “dummy” outputs with consistent record nonces.

Security

This PR is not meant to impact any validator operations, because the CallStack::Synthesize is only used by provers, not by validators/verifiers.

Note

This PR changes expected future IDs in 3 of the execute_and_finalize tests. The reason is that previously, Synthesize always ran real sub-circuits, consuming RNG draws. With this PR, certain sub-circuits are skipped by producing dummy outputs. As a result, the RNG is executed less times, leading to different transaction commitments and future IDs.

Test Plan

Tested the deployment and execution of programs with deep imports in a local devnet.

Related PRs

• Reduce overhead of programs with deep nested imports #2176
• Use evaluate_function for CallStack::PackageRun; Sample response for CallStack::CheckDeployment #2230

[vicsn]

NOTE: this PR will also significantly speed up tests using nested deployments, e.g. test_deep_nested_execution_cost.

[kpandl]

note: the failing snarkvm CI test is a CI/CDN issue

[raychu86]

@d0cd This may be relevant to some of your Stack related work

[vicsn]

LGTM, CI flakiness is unrelated