备份与迷雾的差异分析、合并执行，附属数据改挂坐标键

备份（.rondbackup）与迷雾（.fwss）各加一层「先看差异再动手」：

- 迷雾：上传先出差异页，说清叠加能补多少、整体替换会丢多少，并在真实底图上
  用绿/灰/红标出会新增 / 不变 / 会丢的区域
- 备份：与当前数据集按 UUID 逐条比对（rond 每次导出都会重排 Z_PK，编号认不出人），
  新增合入、冲突逐条选、仅站内有逐条勾选删除，全在一个事务里执行；
  合入的行写回 entity_raw，保证再传同一份备份时差异归零
- 地点按坐标对齐：站点的「补全地址」会把地点改名，拿名称当键会让一整个地点的
  到访全变成假冲突
- 附属数据（备注/结论/访客票/图片）从 dataset_id+src_pk 换成坐标键，换数据集不再失联；
  访客票没有 dataset_id，回填按活跃数据集认领
- 修正 contentHash 拿 Z_PK 当指纹的隐患，以及两处「src_pk 跨快照稳定」的错误注释

导出格式（.rondbackup / .fwss）保持原样，往返测试通过。

internal/web/handlers_admin.go

@@ -769,12 +769,12 @@ func (s *Server) notesPage(w http.ResponseWriter, r *http.Request) {
 	case "note":
 		order = "n.updated_at DESC NULLS LAST, p.name"
 	case "talk":
-		order = "(COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.src_pk = p.src_pk),0)) DESC, p.visit_count DESC"
+		order = "(COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.place_key = " + placeKeyExpr + "),0)) DESC, p.visit_count DESC"
 	}
 
 	base := `FROM places p
-		LEFT JOIN place_notes n ON n.src_pk = p.src_pk AND n.dataset_id = p.dataset_id
-		LEFT JOIN place_votes v ON v.src_pk = p.src_pk AND v.dataset_id = p.dataset_id
+		LEFT JOIN place_notes n ON n.place_key = ` + placeKeyExpr + `
+		LEFT JOIN place_votes v ON v.place_key = ` + placeKeyExpr + `
 		WHERE ` + strings.Join(where, " AND ")
 
 	var total int
@@ -790,8 +790,8 @@ func (s *Server) notesPage(w http.ResponseWriter, r *http.Request) {
 
 	limitArgs := append(append([]any{}, args...), notesPerPage, (d.PageNo-1)*notesPerPage)
 	q2 := `SELECT p.src_pk, COALESCE(n.alias,''), COALESCE(n.note,''), COALESCE(n.rond_note,''), COALESCE(v.verdict,0),
-		COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.src_pk=p.src_pk AND vv.vote=1),0),
-		COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.src_pk=p.src_pk AND vv.vote=-1),0),
+		COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.place_key = ` + placeKeyExpr + ` AND vv.vote=1),0),
+		COALESCE((SELECT count(*) FROM place_visitor_votes vv WHERE vv.place_key = ` + placeKeyExpr + ` AND vv.vote=-1),0),
 		COALESCE(n.updated_at, to_timestamp(0)), p.id, COALESCE(p.name,''), COALESCE(p.city,''), COALESCE(p.visit_count,0)
 		` + base + ` ORDER BY ` + order + fmt.Sprintf(` LIMIT $%d OFFSET $%d`, len(args)+1, len(args)+2)