refactor: 合并 PR 描述生成和 AI 代码审查到仓库详情页

- 新增 PR 描述 tab：流式生成 + 双栏实时预览（渲染效果 + Markdown 源码）
- 新增 AI 代码审查 tab：Top-N/并发设置、历史记录、进度条、总结、备注、PDF 导出、内联 Diff
- 保留 Diff 视图中的 AI 评审快捷内联按钮
- Repo handler 传递 TopN/Concurrency 设置
- 删除独立的 generate.html 和 review.html 页面及路由

handlers/pages.go

@@ -39,18 +39,6 @@ func (h *PageHandler) Index(c *gin.Context) {
 }
 
 func (h *PageHandler) Repo(c *gin.Context) {
-	data := userData(c)
-	data["ID"] = c.Param("id")
-	c.HTML(http.StatusOK, "pages/repo.html", data)
-}
-
-func (h *PageHandler) Generate(c *gin.Context) {
-	data := userData(c)
-	data["ID"] = c.Param("id")
-	c.HTML(http.StatusOK, "pages/generate.html", data)
-}
-
-func (h *PageHandler) Review(c *gin.Context) {
 	user := GetCurrentUser(c)
 	topN := "20"
 	concurrency := "5"
@@ -68,7 +56,7 @@ func (h *PageHandler) Review(c *gin.Context) {
 	data["ID"] = c.Param("id")
 	data["TopN"] = topN
 	data["Concurrency"] = concurrency
-	c.HTML(http.StatusOK, "pages/review.html", data)
+	c.HTML(http.StatusOK, "pages/repo.html", data)
 }
 
 func (h *PageHandler) Settings(c *gin.Context) {