feat: RSS 订阅源 + 仓库 README

- GET /rss.xml 输出 RSS 2.0（已发布文章，SUNDYNIX_SITE_URL 可配）
- vite 代理补 /rss.xml，页脚 RSS 链接生效
- README：结构、开发流程、环境变量、后端规范、API 速览

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

server/internal/handler/rss.go

@@ -0,0 +1,88 @@
+package handler
+
+import (
+	"encoding/xml"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+
+	"git.sundynix.cn/Blizzard/sundynix-site/server/internal/model"
+)
+
+// RSSHandler 输出博客的 RSS 2.0 订阅源。
+type RSSHandler struct {
+	db      *gorm.DB
+	siteURL string
+}
+
+func NewRSSHandler(db *gorm.DB) *RSSHandler {
+	siteURL := os.Getenv("SUNDYNIX_SITE_URL")
+	if siteURL == "" {
+		siteURL = "https://sundynix.com"
+	}
+	return &RSSHandler{db: db, siteURL: siteURL}
+}
+
+type rssItem struct {
+	Title       string `xml:"title"`
+	Link        string `xml:"link"`
+	GUID        string `xml:"guid"`
+	Description string `xml:"description"`
+	Category    string `xml:"category,omitempty"`
+	PubDate     string `xml:"pubDate"`
+}
+
+type rssFeed struct {
+	XMLName xml.Name `xml:"rss"`
+	Version string   `xml:"version,attr"`
+	Channel struct {
+		Title       string    `xml:"title"`
+		Link        string    `xml:"link"`
+		Description string    `xml:"description"`
+		Language    string    `xml:"language"`
+		Items       []rssItem `xml:"item"`
+	} `xml:"channel"`
+}
+
+// Feed GET /rss.xml
+func (h *RSSHandler) Feed(c *gin.Context) {
+	var posts []model.PostListItem
+	err := h.db.Model(&model.Post{}).
+		Where("published_at IS NOT NULL").
+		Order("published_at DESC").
+		Limit(50).
+		Find(&posts).Error
+	if err != nil {
+		c.String(http.StatusInternalServerError, "feed unavailable")
+		return
+	}
+
+	feed := rssFeed{Version: "2.0"}
+	feed.Channel.Title = "sundynix agentix 博客"
+	feed.Channel.Link = h.siteURL + "/blog"
+	feed.Channel.Description = "事件驱动的 AI Agent 工作台 — 发布日志与工程笔记"
+	feed.Channel.Language = "zh-cn"
+	for _, p := range posts {
+		link := h.siteURL + "/blog/" + p.Slug
+		item := rssItem{
+			Title:       p.Title,
+			Link:        link,
+			GUID:        link,
+			Description: p.Summary,
+			Category:    p.Category,
+		}
+		if p.PublishedAt != nil {
+			item.PubDate = p.PublishedAt.Format(time.RFC1123Z)
+		}
+		feed.Channel.Items = append(feed.Channel.Items, item)
+	}
+
+	c.Header("Content-Type", "application/rss+xml; charset=utf-8")
+	c.String(http.StatusOK, xml.Header)
+	if out, err := xml.MarshalIndent(feed, "", "  "); err == nil {
+		c.Writer.Write(out)
+	}
+}

server/internal/router/router.go

@@ -30,6 +30,9 @@ func New(db *gorm.DB) (*gin.Engine, error) {
 		api.GET("/posts/:slug", posts.Get)
 	}
 
+	// RSS 订阅源（页脚 RSS 链接指向这里）
+	r.GET("/rss.xml", handler.NewRSSHandler(db).Feed)
+
 	// ── 管理端 API ──
 	adminAuth := handler.NewAdminAuthHandler()
 	api.POST("/admin/login", adminAuth.Login)