✨ Add explanatory comment for deferred imports

Document why generate_banner and generate_logo are imported inside the
function rather than at module scope.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Ralph Agent

onboard.py

@@ -454,6 +454,7 @@ def _check_gemini_key() -> bool:
 
 def _run_media_generation(choice: str, project_name: str, theme: str) -> list[str]:
     """Run the selected media generation and return list of generated file paths."""
+    # Import here to avoid requiring GEMINI_API_KEY for non-media commands
     from init.generate_banner import generate_banner as gen_banner
     from init.generate_logo import generate_logo as gen_logo