feat: v3 增强 - FTS5全文搜索+双向链接/知识图谱+自动保存草稿+标签管理+实时预览编辑器+PWA

- FTS5中文分词搜索(需-tags=sqlite_fts5)
- [[wiki链接]]反向链接+SVG知识图谱
- 自动保存草稿(不触发版本历史)
- 标签重命名/合并/删除+使用统计
- 后台编辑实时预览+格式工具栏
- PWA manifest+service worker+移动端适配
- 冒烟测试扩至66例全通过

handler/note_handler.go

@@ -661,3 +661,132 @@ func sanitizeFileName(name string) string {
 	}
 	return name
 }
+
+// ─────────────── 自动保存草稿 ───────────────
+
+// SaveDraft 保存笔记草稿（自动保存）
+func (h *NoteHandler) SaveDraft(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		fail(c, http.StatusBadRequest, "无效的笔记 ID")
+		return
+	}
+	var req struct {
+		Content string `json:"content"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		fail(c, http.StatusBadRequest, "请求参数错误")
+		return
+	}
+	if err := h.svc.SaveDraft(uint(id), req.Content); err != nil {
+		fail(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+	success(c, nil)
+}
+
+// DiscardDraft 清除指定笔记的草稿
+func (h *NoteHandler) DiscardDraft(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		fail(c, http.StatusBadRequest, "无效的笔记 ID")
+		return
+	}
+	if err := h.svc.ClearDraft(uint(id)); err != nil {
+		fail(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+	success(c, nil)
+}
+
+// ─────────────── 双向链接 / 知识图谱 ───────────────
+
+// GetBacklinks 获取指定笔记的反向链接列表
+func (h *NoteHandler) GetBacklinks(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		fail(c, http.StatusBadRequest, "无效的笔记 ID")
+		return
+	}
+	links, err := h.svc.GetBacklinks(uint(id), "")
+	if err != nil {
+		fail(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+	success(c, links)
+}
+
+// GetKnowledgeGraph 获取知识图谱数据（节点 + 边）
+func (h *NoteHandler) GetKnowledgeGraph(c *gin.Context) {
+	graph, err := h.svc.GetKnowledgeGraph()
+	if err != nil {
+		fail(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+	success(c, graph)
+}
+
+// ─────────────── 标签管理 ───────────────
+
+// GetTagUsage 获取标签及使用次数
+func (h *NoteHandler) GetTagUsage(c *gin.Context) {
+	usage, err := h.svc.GetTagUsage()
+	if err != nil {
+		fail(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+	success(c, usage)
+}
+
+// RenameTag 重命名标签
+func (h *NoteHandler) RenameTag(c *gin.Context) {
+	var req struct {
+		OldName string `json:"old_name" binding:"required"`
+		NewName string `json:"new_name" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		fail(c, http.StatusBadRequest, "请求参数错误")
+		return
+	}
+	changed, err := h.svc.RenameTag(req.OldName, req.NewName)
+	if err != nil {
+		fail(c, http.StatusBadRequest, err.Error())
+		return
+	}
+	success(c, gin.H{"changed": changed})
+}
+
+// MergeTag 合并标签（from → to）
+func (h *NoteHandler) MergeTag(c *gin.Context) {
+	var req struct {
+		From string `json:"from" binding:"required"`
+		To   string `json:"to" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		fail(c, http.StatusBadRequest, "请求参数错误")
+		return
+	}
+	changed, err := h.svc.MergeTag(req.From, req.To)
+	if err != nil {
+		fail(c, http.StatusBadRequest, err.Error())
+		return
+	}
+	success(c, gin.H{"changed": changed})
+}
+
+// DeleteTag 删除标签（从所有笔记中移除）
+func (h *NoteHandler) DeleteTag(c *gin.Context) {
+	var req struct {
+		Name string `json:"name" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		fail(c, http.StatusBadRequest, "请求参数错误")
+		return
+	}
+	changed, err := h.svc.DeleteTag(req.Name)
+	if err != nil {
+		fail(c, http.StatusBadRequest, err.Error())
+		return
+	}
+	success(c, gin.H{"changed": changed})
+}