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_headless_service.py

@@ -56,7 +56,7 @@ class TestHeadlessAPI(unittest.TestCase):
      self.assertIn("not configured", response.json()["detail"])
 
     def test_generate_endpoint(self) -> None:
-     with patch('src.ai_client.send_result', return_value=Result(data="AI Response")), \
+     with patch('src.ai_client.send', return_value=Result(data="AI Response")), \
           patch('src.app_controller.AppController._do_generate', return_value=("md", "path", [], "stable", "disc")):
       payload = {"prompt": "test prompt", "auto_add_history": False}
       response = self.client.post("/api/v1/generate", json=payload, headers=self.headers)