fix(tier1): disable tools in generate_tracks, add enable_tools param to ai_client.send

Tier 1 planning calls are strategic — the model should never use file tools
during epic initialization. This caused JSON parse failures when the model
tried to verify file references in the epic prompt.

- ai_client.py: add enable_tools param to send() and _send_gemini()
- orchestrator_pm.py: pass enable_tools=False in generate_tracks()
- tests/visual_sim_mma_v2.py: remove file reference from test epic

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/visual_sim_mma_v2.py

@@ -73,7 +73,7 @@ def test_mma_complete_lifecycle(live_gui) -> None:
     # ------------------------------------------------------------------
     # Keep prompt short and simple so the model returns minimal JSON
     client.set_value('mma_epic_input',
-                     'Add a hello_world() function to utils.py')
+                     'Add a hello_world greeting function to the project')
     time.sleep(0.3)
     client.click('btn_mma_plan_epic')
     time.sleep(0.5)   # frame-sync after click