fix(P0-03): Prediction 幂等指纹——只追加,不覆盖

_upsert_prediction 改为 _insert_or_find_by_fingerprint:
- 同 input_hash → 返回已有行(绝不 UPDATE pred_/reasoning/agent_outputs)
- 不同 input_hash → INSERT 新行

input_hash 升级为规范 JSON SHA-256,捕获:match_id, cutoff, prompt_version,
prompt_hash, system_prompt_hash, provider, model, mode, run_type, temperature,
context_hash, agent_ids。移除旧 (match, provider, model, mode, run_type) 唯一约束,
改为 partial unique index(WHERE input_hash IS NOT NULL,兼容旧 NULL 数据)。

三条路径(single/multi/baseline)统一传足指纹字段。
迁移 0024 + 测试 test_p0_prediction_fingerprint(10/10);全量 295 通过。

tests/test_agent_weights_persist.py

@@ -61,7 +61,7 @@ class TestOrchestratorWritesAgentWeights:
 
     @pytest.mark.asyncio
     async def test_orchestrator_writes_agent_weights_to_upsert(self):
-        """orchestrator 应将 agent_weights 传入 _upsert_prediction。"""
+        """orchestrator 应将 agent_weights 传入 _insert_or_find_by_fingerprint。"""
         from src.llm.agents import orchestrator as orch_mod
         from src.llm.agents.base import AgentReport
         from src.llm.context_builder import MatchHeader
@@ -103,8 +103,8 @@ class TestOrchestratorWritesAgentWeights:
                 "agent_weights": {"form": 0.3, "home_away": 0.5, "stats": 0.2},
             }, 100, 50
 
-        async def mock_upsert(session, **kw):
-            captured_values.update(kw.get("values", {}))
+        async def mock_upsert(session, *, values):
+            captured_values.update(values)
             p = MagicMock()
             p.id = 1
             p.provider = "test"
@@ -116,7 +116,7 @@ class TestOrchestratorWritesAgentWeights:
             p.subjective_confidence = 0.7
             p.reasoning = "test"
             p.agent_outputs = []
-            p.agent_weights = kw["values"].get("agent_weights")
+            p.agent_weights = values.get("agent_weights")
             return p
 
         class FakeUow:
@@ -130,14 +130,14 @@ class TestOrchestratorWritesAgentWeights:
         with patch.object(orch_mod, "run_specialists", mock_specialists), \
              patch.object(orch_mod, "_agent_provider", mock_provider), \
              patch.object(orch_mod, "load_match_header", mock_header), \
-             patch.object(orch_mod, "_upsert_prediction", mock_upsert), \
+             patch.object(orch_mod, "_insert_or_find_by_fingerprint", mock_upsert), \
              patch.object(orch_mod, "run_aggregator", mock_aggregator), \
              patch.object(orch_mod, "get_uow", FakeUow):
 
             result = await orch_mod.predict_match_multi(999)
 
         # 断言 agent_weights 被写入
-        assert "agent_weights" in captured_values, "agent_weights 应传入 _upsert_prediction"
+        assert "agent_weights" in captured_values, "agent_weights 应传入 _insert_or_find_by_fingerprint"
         assert captured_values["agent_weights"] is not None, "agent_weights 不应为 None"
         assert "form" in captured_values["agent_weights"], "agent_weights 应包含专家权重"
         print(f"PASS: agent_weights = {captured_values['agent_weights']}")