feat: improve network topology — LLDP-authoritative, manual links, orphan handling (v0.11.6 Beta)

- Backend: 7-step pipeline — per-neighbor best-protocol dedup, bidirectional
  LLDP pair merging, LLDP-covered set suppression of noisy CDP/MNDP links,
  shared-segment heuristic limited to genuinely unresolved non-LLDP links
- Backend: manual_topology_links table + POST/DELETE endpoints for user-drawn connections
- Frontend: ManualEdge custom edge type (purple dashed + × delete button)
- Frontend: Connect Mode toggle — blue crosshair handles, onConnect creates DB-persisted link
- Frontend: orphan nodes in dedicated bottom row with orange warning banner
- Frontend: legend updated, canvas height increased

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-frontend",
-  "version": "0.11.5-beta",
+  "version": "0.11.6-beta",
   "private": true,
   "type": "module",
   "scripts": {