fix: update all test mocks for call_llm migration

Update 14 test files to use the new call_llm/async_call_llm mock
patterns instead of the old get_text_auxiliary_client/
get_vision_auxiliary_client tuple returns.

- vision_tools tests: mock async_call_llm instead of _aux_async_client
- browser tests: mock call_llm instead of _aux_vision_client
- flush_memories tests: mock call_llm instead of get_text_auxiliary_client
- session_search tests: mock async_call_llm with RuntimeError
- mcp_tool tests: fix whitelist model config, use side_effect for
  multi-response tests
- auxiliary_config_bridge: update for model=None (resolved in router)

3251 passed, 2 pre-existing unrelated failures.

tests/tools/test_browser_console.py

@@ -137,8 +137,7 @@ class TestBrowserVisionAnnotate:
 
         with (
             patch("tools.browser_tool._run_browser_command") as mock_cmd,
-            patch("tools.browser_tool._aux_vision_client") as mock_client,
-            patch("tools.browser_tool._DEFAULT_VISION_MODEL", "test-model"),
+            patch("tools.browser_tool.call_llm") as mock_call_llm,
             patch("tools.browser_tool._get_vision_model", return_value="test-model"),
         ):
             mock_cmd.return_value = {"success": True, "data": {}}
@@ -159,8 +158,7 @@ class TestBrowserVisionAnnotate:
 
         with (
             patch("tools.browser_tool._run_browser_command") as mock_cmd,
-            patch("tools.browser_tool._aux_vision_client") as mock_client,
-            patch("tools.browser_tool._DEFAULT_VISION_MODEL", "test-model"),
+            patch("tools.browser_tool.call_llm") as mock_call_llm,
             patch("tools.browser_tool._get_vision_model", return_value="test-model"),
         ):
             mock_cmd.return_value = {"success": True, "data": {}}