feat(trust): ADR-088 Trust Score 持久化 — L4 自動放行核心

TrustScoreManager 從記憶體升級為 PostgreSQL 持久化，
Pod 重啟後信任分數不再歸零，AI 能真正累積到 L4 自動放行門檻。

變更:
- migrations/adr088_trust_score_persistence.sql: trust_records 表
- db/models.py: TrustRecordDB ORM model
- repositories/interfaces.py: ITrustRepository Protocol
- repositories/trust_repository.py: PG upsert ON CONFLICT DO UPDATE
- services/trust_engine.py: bulk_load() 啟動 warm-up
- services/learning_service.py: _persist_trust() + 2 call sites
- main.py: 啟動時 load_all() → bulk_load()

流程: 批准 5 次 → score=5 寫入 DB → Pod 重啟 → warm-up 讀回
      → evaluate_adjusted_risk MEDIUM→LOW → 自動執行

2026-04-17 ogt + Claude Sonnet 4.6（亞太）: ADR-088

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/db/models.py

@@ -1175,3 +1175,56 @@ class AiGovernanceEvent(Base):
         Index("ix_ai_governance_triggered_at", "triggered_at"),
         Index("ix_ai_governance_resolved", "resolved"),
     )
+
+
+# =============================================================================
+# TrustRecordDB - ADR-088 TrustScore 持久化
+# =============================================================================
+
+class TrustRecordDB(Base):
+    """
+    Trust Score 持久化記錄
+
+    ADR-088: TrustScoreManager 從記憶體升級為 PostgreSQL 持久化。
+    Pod 重啟後分數不歸零，AI 能真正累積信任達到 L4 自動放行。
+
+    score >= 5:  MEDIUM → LOW (自動執行)
+    score >= 10: HIGH → MEDIUM (降一級)
+
+    2026-04-17 ogt + Claude Sonnet 4.6（亞太）: Phase 4 信任持久化
+    """
+    __tablename__ = "trust_records"
+
+    action_pattern: Mapped[str] = mapped_column(
+        String(255), primary_key=True,
+        comment="操作模式，例如 delete:nginx-frontend-*"
+    )
+    score: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+        comment="累積信任分數。+1/approve，reject 歸零"
+    )
+    total_approvals: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+    )
+    total_rejections: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0,
+    )
+    last_approval_by: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    last_approval_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True,
+    )
+    last_rejection_by: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    last_rejection_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True,
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, default=taipei_now,
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, default=taipei_now, onupdate=taipei_now,
+    )
+
+    __table_args__ = (
+        Index("ix_trust_records_score", "score"),
+        Index("ix_trust_records_updated", "updated_at"),
+    )