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>

orchestrator_pm.py

@@ -78,7 +78,8 @@ def generate_tracks(user_request: str, project_config: dict, file_items: list[di
  # Note: We use gemini-1.5-pro or similar high-reasoning model for Tier 1
   response = ai_client.send(
    md_content="", # We pass everything in user_message for clarity
-   user_message=user_message
+   user_message=user_message,
+   enable_tools=False,
   )
   # 4. Parse JSON Output
   try: