Refactor the exporter into a package-backed module layout.

Split the previous monolithic implementation into focused modules for CLI handling, workflow loading, runtime bootstrap, load ordering, planning, rendering, and file I/O. Keep the public compatibility surface intact by preserving the legacy top-level wrapper while adding  as the documented entrypoint. This reduces cross-cutting coupling inside the exporter and makes the runtime/bootstrap behavior easier to evolve without carrying unrelated concerns in one file.

comfyui_to_python/generator/model.py

@@ -0,0 +1,12 @@
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class GenerationPlan:
+    import_statements: dict[str, set[str]]
+    special_functions_code: list[str]
+    loop_code: list[str]
+    workflow_data: dict
+    metadata_workflow_data: dict | None
+    queue_size: int
+    custom_nodes: bool