feat: 易支付积分充值 + 站内公告 + OpenAI 视频修复 + grok/adobe 失败处理

充值/订单(易支付 mapi):
- 订单表 + 30 分钟自动取消;支付弹窗(二维码/跳转监控、倒计时、轮询、5s 倒计时关闭)
- 系统设置可配:开关/商户ID/密钥/支付地址(根地址拼 /mapi)/支付方式/最低额/积分比例(默认 1元=100积分)
- 异步通知 MD5 验签、幂等到账;用户累计充值;前台/后台订单页(筛选+搜索+分页,前后台分风格);用户管理累计充值列

站内公告:
- Markdown 公告,登录用户首次访问/刷新弹出;内容哈希做版本,改了就重新推;管理员不弹;空内容=下线

OpenAI 视频(/v1/videos)修复:
- /content 拿不到视频:grok 资源 URL 需鉴权,改为用生成账号 token 取流;adobe/runway 公开 URL 直代理(不存 RustFS)
- size→分辨率用短边判定(1280x720 = 720p,之前误判 1080p 被拒)

失败处理:
- grok 429「Too many requests」/403 anti-bot 改判临时错误(不再误封号),真额度耗尽才算 quota
- adobe 视频 408 / system under load 归为临时错误 → tempAsDead 封号

其它:
- 充值默认关闭;签到格子浅色可见;登录验证码按钮浅色可读;并发/账户信息展示
- 创作记录/画图台只显示画图台作品(排除 API);日志页 API 视频预览显示 —
- 视频去画中画/下载/投屏(全局);图片缩略图改背景图规避 Edge 视觉搜索
- 订单/兑换码/配置/日志菜单文案与图标;充值版块样式

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/http/handler/announcement.go

@@ -0,0 +1,65 @@
+package handler
+
+import (
+	"net/http"
+
+	"backend/internal/service"
+	"github.com/gin-gonic/gin"
+)
+
+type AnnouncementHandler struct {
+	svc *service.AnnouncementService
+}
+
+func NewAnnouncementHandler(svc *service.AnnouncementService) *AnnouncementHandler {
+	return &AnnouncementHandler{svc: svc}
+}
+
+// Get — logged-in user: the current announcement + whether THIS user has seen it.
+func (h *AnnouncementHandler) Get(c *gin.Context) {
+	user := currentUser(c)
+	if user == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"detail": "未登录或会话已过期"})
+		return
+	}
+	c.JSON(http.StatusOK, h.svc.ForUser(c.Request.Context(), user))
+}
+
+// MarkSeen — user dismissed the announcement of the given version.
+func (h *AnnouncementHandler) MarkSeen(c *gin.Context) {
+	user := currentUser(c)
+	if user == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"detail": "未登录或会话已过期"})
+		return
+	}
+	var body struct {
+		Version string `json:"version"`
+	}
+	_ = c.ShouldBindJSON(&body)
+	if err := h.svc.MarkSeen(c.Request.Context(), user.ID, body.Version); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"detail": "failed to save"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// AdminGet — admin editor: the raw markdown.
+func (h *AnnouncementHandler) AdminGet(c *gin.Context) {
+	c.JSON(http.StatusOK, gin.H{"content": h.svc.Content(c.Request.Context())})
+}
+
+// AdminPut — admin saves new markdown (re-pops for everyone who hasn't seen it).
+func (h *AnnouncementHandler) AdminPut(c *gin.Context) {
+	var body struct {
+		Content string `json:"content"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"detail": "invalid request body"})
+		return
+	}
+	if err := h.svc.Save(c.Request.Context(), body.Content); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"detail": "failed to save"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}