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_context_pruner.py

@@ -105,7 +105,7 @@ def test_token_reduction_logging(capsys):
  with pytest.MonkeyPatch().context() as m:
   m.setattr("builtins.open", lambda f, *args, **kwargs: type('obj', (object,), {'read': lambda s: code, '__enter__': lambda s: s, '__exit__': lambda s, *a: None})())
   m.setattr("pathlib.Path.exists", lambda s: True)
-  m.setattr("src.ai_client.send_result", lambda **kwargs: Result(data="DONE"))
+  m.setattr("src.ai_client.send", lambda **kwargs: Result(data="DONE"))
   
   run_worker_lifecycle(ticket, context, context_files=["test.py"])