test(ai_client): rename send_result to send in 22 remaining test files

Batch rename of 22 test files. 62 references renamed total.

The full test suite is now GREEN again, matching the pre-rename baseline
from Task 1.1. Pure mechanical rename. No behavior change.

Files affected: test_ai_cache_tracking, test_ai_client_cli,
test_ai_client_result, test_api_events, test_context_pruner,
test_deepseek_provider, test_gemini_cli_* (3 files), test_gui2_mcp,
test_headless_* (2 files), test_live_gui_integration_v2,
test_orchestration_logic, test_phase6_engine, test_rag_integration,
test_run_worker_lifecycle_abort, test_spawn_interception_v2,
test_symbol_parsing, test_tier4_interceptor, test_tiered_aggregation,
test_token_usage.

Note: spec estimated 24 files; actual is 22 (test_deprecation_warnings
no longer exists, and 1 fewer file than spec's list).

Refs: conductor/tracks/send_result_to_send_20260616/

tests/test_phase6_engine.py

@@ -10,7 +10,7 @@ def test_worker_streaming_intermediate():
  event_queue = MagicMock()
 
  with (
-  patch("src.ai_client.send_result") as mock_send_result,
+  patch("src.ai_client.send") as mock_send,
   patch("src.multi_agent_conductor._queue_put") as mock_q_put,
   patch("src.multi_agent_conductor.confirm_spawn", return_value=(True, "p", "c")),
   patch("src.ai_client.reset_session"),
@@ -26,7 +26,7 @@ def test_worker_streaming_intermediate():
     cb({"kind": "tool_result", "payload": {"name": "test_tool", "output": "hello"}})
    return Result(data="DONE")
 
-  mock_send_result.side_effect = side_effect
+  mock_send.side_effect = side_effect
   run_worker_lifecycle(ticket, context, event_queue=event_queue)
 
   # _queue_put(event_queue, event_name, payload)