fix: 恢复 V1 原样，site_type 改动迁移到 V5

- V1: 恢复到原始 DEFAULT 'private' + 原始注释
- V5: ALTER TABLE sites MODIFY site_type DEFAULT 'unknown'
- 彻底解决 Flyway checksum 冲突，不改 flyway_schema_history

par-api/src/main/resources/application.yml

@@ -31,7 +31,6 @@ spring:
     locations: classpath:db/migration
     baseline-on-migrate: true
     baseline-version: 0
-    validate-on-migrate: false
 
 mybatis-plus:
   configuration:

par-core/src/main/resources/db/migration/V1__init_schema.sql

@@ -30,7 +30,7 @@ CREATE TABLE sites (
     description         TEXT                COMMENT '站点描述',
     base_url            VARCHAR(500)        COMMENT '站点基础URL',
     icon_url            VARCHAR(500)        COMMENT '站点图标URL',
-    site_type           VARCHAR(50)         NOT NULL DEFAULT 'unknown' COMMENT '站点引擎类型: nexusphp/mtorrent/mteam/...',
+    site_type           VARCHAR(50)         NOT NULL DEFAULT 'private' COMMENT '站点类型: private/public/xxx',
     schema_version      VARCHAR(20)         NOT NULL DEFAULT '1.0.0' COMMENT '当前生效的schema版本',
     current_config_id   BIGINT UNSIGNED     COMMENT '当前生效的配置版本ID（site_configs.id）',
     status              VARCHAR(20)         NOT NULL DEFAULT 'active' COMMENT '站点状态: active/pending/deprecated',

par-core/src/main/resources/db/migration/V5__site_type_fix.sql

@@ -0,0 +1,4 @@
+-- PAR Flyway V5: 站点类型字段修正（从 V1 回退中提取）
+-- 统一 site_type 默认值和注释，与 SiteType 枚举对齐
+ALTER TABLE sites
+    MODIFY COLUMN site_type VARCHAR(50) NOT NULL DEFAULT 'unknown' COMMENT '站点引擎类型: nexusphp/mtorrent/mteam/...';