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_test.go

@@ -7,6 +7,8 @@ import (
 	"context"
 	"testing"
 
+	"github.com/Rain-kl/Wavelet/internal/repository"
+
 	"github.com/Rain-kl/Wavelet/internal/apps/openflare/agent"
 	db "github.com/Rain-kl/Wavelet/internal/infra/persistence"
 	"github.com/Rain-kl/Wavelet/internal/model"
@@ -62,7 +64,7 @@ func TestHeartbeatFlaredEmitsHealthEventOnUnhealthy(t *testing.T) {
 	})
 	require.NoError(t, err)
 
-	events, err := model.ListOpenFlareHealthEvents(ctx, node.NodeID, false, 20)
+	events, err := repository.ListOpenFlareHealthEvents(ctx, node.NodeID, false, 20)
 	require.NoError(t, err)
 	require.Len(t, events, 1)
 	assert.Equal(t, flaredRuntimeUnhealthyEventType, events[0].EventType)