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>

ai_client.py

@@ -621,14 +621,15 @@ def _send_gemini(md_content: str, user_message: str, base_dir: str,
  file_items: list[dict[str, Any]] | None = None,
  discussion_history: str = "",
  pre_tool_callback: Optional[Callable[[str], bool]] = None,
- qa_callback: Optional[Callable[[str], str]] = None) -> str:
+ qa_callback: Optional[Callable[[str], str]] = None,
+ enable_tools: bool = True) -> str:
  global _gemini_chat, _gemini_cache, _gemini_cache_md_hash, _gemini_cache_created_at
  try:
   _ensure_gemini_client(); mcp_client.configure(file_items or [], [base_dir])
   # Only stable content (files + screenshots) goes in the cached system instruction.
   # Discussion history is sent as conversation messages so the cache isn't invalidated every turn.
   sys_instr = f"{_get_combined_system_prompt()}\n\n<context>\n{md_content}\n</context>"
-  td = _gemini_tool_declaration()
+  td = _gemini_tool_declaration() if enable_tools else None
   tools_decl = [td] if td else None
   # DYNAMIC CONTEXT: Check if files/context changed mid-session
   current_md_hash = hashlib.md5(md_content.encode()).hexdigest()
@@ -1628,6 +1629,7 @@ def send(
  stream: bool = False,
  pre_tool_callback: Optional[Callable[[str], bool]] = None,
  qa_callback: Optional[Callable[[str], str]] = None,
+ enable_tools: bool = True,
 ) -> str:
  """
     Send a message to the active provider.
@@ -1646,7 +1648,7 @@ def send(
     """
  with _send_lock:
   if _provider == "gemini":
-   return _send_gemini(md_content, user_message, base_dir, file_items, discussion_history, pre_tool_callback, qa_callback)
+   return _send_gemini(md_content, user_message, base_dir, file_items, discussion_history, pre_tool_callback, qa_callback, enable_tools=enable_tools)
   elif _provider == "gemini_cli":
    return _send_gemini_cli(md_content, user_message, base_dir, file_items, discussion_history, pre_tool_callback, qa_callback)
   elif _provider == "anthropic":