refactor(backend): 添加 service 缓存端口

backend/internal/repository/update_cache.go

@@ -0,0 +1,28 @@
+package repository
+
+import (
+	"context"
+	"time"
+
+	"sub2api/internal/service/ports"
+
+	"github.com/redis/go-redis/v9"
+)
+
+const updateCacheKey = "update:latest"
+
+type updateCache struct {
+	rdb *redis.Client
+}
+
+func NewUpdateCache(rdb *redis.Client) ports.UpdateCache {
+	return &updateCache{rdb: rdb}
+}
+
+func (c *updateCache) GetUpdateInfo(ctx context.Context) (string, error) {
+	return c.rdb.Get(ctx, updateCacheKey).Result()
+}
+
+func (c *updateCache) SetUpdateInfo(ctx context.Context, data string, ttl time.Duration) error {
+	return c.rdb.Set(ctx, updateCacheKey, data, ttl).Err()
+}