feat(canvas): 画布同步 - 新增操作事务、预演保存与并发恢复能力

backend/internal/database/migrations.go

@@ -11,7 +11,7 @@ import (
 	"gorm.io/gorm"
 )
 
-const CurrentSchemaVersion int64 = 49
+const CurrentSchemaVersion int64 = 50
 
 const baselineSchemaChecksum = "sha256:open-ai-canvas-schema-v1-20260830"
 const schemaMigrationAppliedAtIndexChecksum = "sha256:schema-migrations-applied-at-index-v2-20260830"
@@ -163,6 +163,9 @@ var schemaMigrations = []migration{
 		}
 		return nil
 	}},
+	{version: 50, name: "canvas_mutation_receipts", checksum: "sha256:canvas-mutation-receipts-v50-20261011", apply: func(tx *gorm.DB) error {
+		return tx.AutoMigrate(&model.CanvasMutationReceipt{})
+	}},
 }
 
 func migratePrefixedIDSequenceReconcile(tx *gorm.DB) error {

backend/internal/database/schema.go

@@ -102,6 +102,7 @@ func Models() []any {
 		&model.CanvasProject{},
 		&model.CanvasSnapshot{},
 		&model.CanvasSnapshotResource{},
+		&model.CanvasMutationReceipt{},
 		&model.CanvasShare{},
 		&model.PromptTemplate{},
 		&model.UserPromptCustomization{},