fix(tests): carry render_runtime into e2e edit_decisions fixture (#69)

tests/qa/test_08_end_to_end.py runs at module import, so pytest fails
collection with CheckpointValidationError: the Stage 5 edit_decisions
fixture omits render_runtime, which edit_decisions.schema.json lists as
required. Per AGENT_GUIDE the runtime is locked at proposal and carried
through edit unchanged, so the fixture now sources it from the same
proposal_packet["production_plan"]["render_runtime"] ("remotion")
instead of hardcoding an unrelated value, keeping the fixture internally
consistent with the proposal it builds on.

tests/qa/test_08_end_to_end.py

@@ -424,6 +424,7 @@ for i, scene in enumerate(scene_plan["scenes"]):
 
 edit_decisions = {
     "version": "1.0",
+    "render_runtime": proposal_packet["production_plan"]["render_runtime"],
     "cuts": [
         {
             "id": f"cut_{scene['id']}",