feat: add props system and refactor asset library architecture

prisma/schema.prisma

@@ -104,6 +104,7 @@ model NovelPromotionLocation {
   novelPromotionProjectId String
   name                    String
   summary                 String?               @db.Text // 场景简要描述（用途/人物关联）
+  assetKind               String                @default("location")
   createdAt               DateTime              @default(now())
   updatedAt               DateTime              @default(now()) @updatedAt
   sourceGlobalLocationId  String? // 🆕 来源全局场景ID（复制时记录）
@@ -170,6 +171,7 @@ model NovelPromotionClip {
   createdAt  DateTime                  @default(now())
   updatedAt  DateTime                  @default(now()) @updatedAt
   characters String?                   @db.Text
+  props      String?                   @db.Text
   endText    String?                   @db.Text
   shotCount  Int?
   startText  String?                   @db.Text
@@ -192,6 +194,7 @@ model NovelPromotionPanel {
   description       String?                   @db.Text
   location          String?                   @db.Text
   characters        String?                   @db.Text
+  props             String?                   @db.Text
   srtSegment        String?                   @db.Text
   srtStart          Float?
   srtEnd            Float?
@@ -878,6 +881,7 @@ model GlobalLocation {
   name      String
   artStyle  String?
   summary   String?  @db.Text
+  assetKind String   @default("location")
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt