feat(wave6-8): P2.1 fusion + P2.2 governance + P2.4 consensus + Wave 7/8 BLOCKER 修復

承接 Wave 6/7/8 多 engineer 在 agent 限額前完成的代碼，補 commit 解 production
HEAD 隱性 import error（decision_fusion 已被 decision_manager 引用但檔案 untracked）。

新增（後端核心）:
- decision_fusion.py (562 行) — P2.1 方法 III（OpenClaw + Hermes + Elephant 三 LLM 融合）
- aiops_timeline.py + aiops_timeline_service.py — critic B4 修復
  /api/v1/aiops/timeline endpoint，DB 存取抽到 service 層遵守 leWOOOgo 積木化
- migrations/p2_decision_fusion_columns.sql + rollback — approval_records fusion 欄位

修改（後端整合）:
- decision_manager.py — fusion 三斷鏈修補（critic B1+B2+B3）：
  · B1: 寫 _evidence_snapshot_ref 到 token.proposal_data
  · B2: fusion 前計算 complexity_score 並寫 token
  · B3: fusion composite 寫 token.proposal_data["decision_fusion"]
- auto_approve.py — fusion + consensus 認識（critic B3+B5）：
  · composite > 0.7 → auto_execute_eligible bypass min_confidence
  · source=consensus_engine + score>=0.6 → 規則可信路徑
- consensus_engine.py — db-fix _save_consensus 重用 agent_sessions
- governance_agent.py — db-fix _alert PG 寫入 ai_governance_events
- approval_db.py — fusion 3 欄位 + 2 partial index + CheckConstraint
- db/models.py — schema 對齊 migration
- core/config.py — vuln #1 修復：OLLAMA_URL/_FALLBACK_URL field_validator
  拒絕公網 IP + 外部域名，僅允許私網/loopback/K8s SVC 白名單
- core/feature_flags.py — P2 fusion + consensus flags
- main.py — governance_agent lifespan 啟動
- failover_alerter.py — Wave8-X2: in-memory dedup fallback（Redis 拒絕後不 fail-open）
- ollama_*.py — metrics 整合 + recovery 改善
- auto_repair_service.py — verifier 接線

新增（測試 2438 行）:
- test_decision_fusion.py / test_governance_agent.py / test_consensus_integration.py
- test_p2_db_fixes.py / test_wave8_fusion_fixes.py
- test_config_url_validation.py（vuln #1 12 tests）
- test_failover_alerter.py +Wave8-X2 in-memory dedup 補測

驗收: 116 tests pass (decision_fusion + wave8_fusion + config_url + consensus +
                      governance + p2_db_fixes + failover_alerter)

Conflict resolution:
- 3 檔（config.py + auto_approve.py + decision_manager.py）git stash pop 衝突
  保留 stashed (engineer 最終版)，補回 ValueError 「公網 IP」字樣對齊 test

Note: 此 commit 解 production HEAD 隱性 import error
仍未修: vuln #4 prompt injection / debugger B14 quota fail-closed
       / B25-B26 drain_pending_tasks / B8 governance fail alert

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-Authored-By: Multiple Engineers (Wave 6/7/8) <noreply@anthropic.com>

apps/api/src/services/approval_db.py

@@ -786,6 +786,54 @@ class ApprovalDBService:
         )
         return rowcount
 
+    async def update_decision_fusion(
+        self,
+        incident_id: str,
+        composite_score: float,
+        complexity_tier: str,
+        fusion_details: dict,
+    ) -> int:
+        """
+        P2.1 DecisionFusionEngine 結果回寫到 approval_records。
+
+        2026-04-26 P2-DB-Fix by Claude — db-expert P0 三修（P0.3）:
+        ADR-085 鐵律：fusion 分數必須落地 PG，不能只存 Redis token
+
+        Args:
+            incident_id: INC-xxx 格式 Incident ID
+            composite_score: FusionScore.composite（0.0-1.0）
+            complexity_tier: ComplexityTier.value（low/medium/high/critical）
+            fusion_details: FusionScore.to_dict() 完整 dict
+
+        Returns:
+            int: rowcount（0 表示找不到對應 PENDING approval）
+        """
+        async with get_db_context() as db:
+            result = await db.execute(
+                update(ApprovalRecord)
+                .where(
+                    and_(
+                        ApprovalRecord.incident_id == incident_id,
+                        ApprovalRecord.status == ApprovalStatus.PENDING,
+                    )
+                )
+                .values(
+                    composite_score=composite_score,
+                    complexity_tier=complexity_tier,
+                    decision_fusion_details=fusion_details,
+                )
+            )
+            rowcount = result.rowcount if hasattr(result, "rowcount") else -1
+
+        logger.info(
+            "approval_decision_fusion_updated",
+            incident_id=incident_id,
+            composite_score=composite_score,
+            complexity_tier=complexity_tier,
+            rowcount=rowcount,
+        )
+        return rowcount
+
     # =========================================================================
     # Phase 6.4h: Proposals API 支援方法
     # =========================================================================