refactor(repository): 收敛 model/repository 分层为唯一持久化入口

将 OpenFlare 与平台业务的数据访问从 model 与 apps 直连迁入 repository，
model 仅保留实体与无 IO 规则；补充 code-check 架构守卫与开发规范。

internal/apps/openflare/flared/observability.go

@@ -10,7 +10,6 @@ import (
 	"time"
 
 	"github.com/Rain-kl/Wavelet/internal/apps/openflare/agent"
-	db "github.com/Rain-kl/Wavelet/internal/infra/persistence"
 	"go.uber.org/zap"
 )
 
@@ -40,11 +39,7 @@ func persistFlaredObservability(ctx context.Context, nodeID string, payload Hear
 			},
 		})
 	}
-	conn := db.DB(ctx)
-	if conn == nil {
-		return
-	}
-	if err := agent.ReconcileScopedNodeHealthEvents(conn, nodeID, events, reportedAt, managedTypes); err != nil {
+	if err := agent.ReconcileScopedNodeHealthEvents(ctx, nodeID, events, reportedAt, managedTypes); err != nil {
 		zap.L().Error("persist flared health events failed", zap.String("node_id", nodeID), zap.Error(err))
 	}
 }