fix(test): update test_ai_loop_regressions_20260614 to patch provider_state.get_history

The Phase 7 alias removal exposed a pre-existing test that patched
src.ai_client._minimax_history and src.ai_client._minimax_history_lock.
Those aliases no longer exist (deleted in Phase 7). Update the test to
patch src.provider_state.get_history with a side_effect that returns a
fresh empty ProviderHistory for 'minimax' and passes through other
providers. This is the canonical pattern for tests that need to
intercept the new provider_state.get_history(...) calls.

tests/test_ai_loop_regressions_20260614.py

@@ -212,16 +212,19 @@ def test_fr3_minimax_thinking_in_returned_text() -> None:
   ))
 
  from src import openai_compatible as oc
+ from src import provider_state
+ from src.provider_state import ProviderHistory
  from src.vendor_capabilities import register, VendorCapabilities
  register(VendorCapabilities(vendor="minimax", model="MiniMax-M2.7", reasoning=True))
  ai_client._model = "MiniMax-M2.7"
 
+ empty_minimax = ProviderHistory()
+
  with patch.object(oc, "send_openai_compatible", side_effect=_fake_send_openai_compatible), \
       patch("src.ai_client._ensure_minimax_client", return_value=MagicMock()), \
       patch("src.ai_client._get_deepseek_tools", return_value=[]), \
       patch("src.ai_client._trim_minimax_history", side_effect=lambda msgs, h: None), \
-      patch("src.ai_client._minimax_history", new=[]), \
-      patch("src.ai_client._minimax_history_lock", new=MagicMock()):
+      patch("src.provider_state.get_history", side_effect=lambda p: empty_minimax if p == "minimax" else provider_state._PROVIDER_HISTORIES[p]):
   result = ai_client._send_minimax("system", "user", ".", None, "", False, None, None, None)
 
  assert isinstance(result, Result), f"_send_minimax must return a Result, got {type(result).__name__}"