Compile supported workflows into external agent frameworks (LangGraph, smolagents)

[cmccomb]

Summary: Add an opt-in compiler/export layer that turns supported Workflow and CompiledExecution graphs into equivalent artifacts for external agent frameworks such as LangGraph and smolagents.

Why:

• Author study workflows once in design_research_agents.workflow, then run the same logic in other agent ecosystems.
• Make interoperability and cross-framework benchmarking easier without hand-rewriting nodes, edges, and state handoff rules.
• Reuse framework-specific tooling and runtime surfaces while keeping this repo's workflow-first API as the source of truth.

Tasks:

• Define a small public compiler/adapter surface for exporting supported workflow graphs.
• Start with a clearly documented supported subset of deterministic workflow semantics and reject unsupported features with clear validation errors.
• Implement a LangGraph compiler that maps workflow steps and dependencies into a StateGraph or equivalent runnable.
• Implement a smolagents compiler/adapter for the subset that can be represented there, even if that requires a wrapper around framework-native agents/tools.
• Preserve enough metadata to keep ExecutionResult provenance, step IDs, and tracing correlation intelligible after compilation.
• Add parity tests and examples showing the same internal workflow compiled into both frameworks.

Acceptance Criteria:

• A user can export a supported workflow into LangGraph and smolagents from a documented public entry point.
• Unsupported step types or control-flow semantics fail fast with explicit validation messages.
• Examples and docs show the supported subset, dependency extras, and known behavior differences.
• Tests cover equivalence for at least one linear workflow and one branched workflow within the supported subset.