fix(hf): install runtime deps directly and add src to path for HF Space build

HF's Gradio build runs pip install before copying the repo, so 'requirements.txt: -e .' failed (no pyproject.toml in /app). List runtime deps directly and put src/ on sys.path in app.py instead.

app.py

@@ -1,9 +1,17 @@
 from __future__ import annotations
 
 import os
+import sys
 from pathlib import Path
 
-from world_simulator.api.gradio_app import create_gradio_app
+# The project uses a src-layout. On Hugging Face Spaces the package is not
+# pip-installed (requirements.txt lists runtime deps directly, because HF runs
+# pip install before copying the repo into the build context), so make the
+# src/ directory importable here. Harmless locally where the package is already
+# installed in editable mode.
+sys.path.insert(0, str(Path(__file__).parent / "src"))
+
+from world_simulator.api.gradio_app import create_gradio_app  # noqa: E402
 
 app = create_gradio_app(
     config_path=Path(os.getenv("WORLD_SIMULATOR_CONFIG", "config/game.modal.local.json")),

requirements.txt

@@ -1 +1,2 @@
--e .
+gradio>=6.17.3
+openai>=1.0