feat(push): implement Redis caching for push events and custom channels

- Implement cached queries in GetActivePushEventByKey and GetActivePushChannelByName.
- Set TTL for cached items to 24 hours via activePushEventCacheTTL and activePushChannelCacheTTL constants.
- Implement GORM hooks (AfterSave and AfterDelete) on PushEvent and PushChannel to auto-evict Redis caches, guaranteeing cache consistency.
- Evict Redis caches manually inside API handlers for Create/Update/Delete/Toggle event/channel endpoints.
- Update events.go to query models through the new caching methods.

internal/apps/admin/push/channels.go

@@ -107,6 +107,9 @@ func CreateChannel(c *gin.Context) {
 		return
 	}
 
+	// 缓存一致性：清除渠道缓存
+	model.DeleteActivePushChannelCache(ctx, channel.Name)
+
 	c.JSON(http.StatusOK, response.OK(channel))
 }
 
@@ -174,6 +177,9 @@ func UpdateChannel(c *gin.Context) {
 		return
 	}
 
+	// 缓存一致性：清除渠道缓存
+	model.DeleteActivePushChannelCache(ctx, channel.Name)
+
 	c.JSON(http.StatusOK, response.OK(channel))
 }
 
@@ -210,6 +216,9 @@ func DeleteChannel(c *gin.Context) {
 		return
 	}
 
+	// 缓存一致性：清除渠道缓存
+	model.DeleteActivePushChannelCache(ctx, channel.Name)
+
 	c.JSON(http.StatusOK, response.OKNil())
 }