feat: Copy VLANs wizard + CPU display fix for hardware switches (v0.11.0 Beta)

Add 'Copy VLANs from Another Switch' — a 3-step modal available on the
VLANs tab of any switch device. Step 1 selects a source switch and which
VLAN IDs to copy (VLAN 1 deselected by default with a management risk
warning). Step 2 lets the user assign interfaces on the target device
per VLAN: clicking a port chip cycles it through None → Tagged → Untagged
→ None, with a live summary and bridge picker per VLAN. Conflict detection
identifies VLANs already present on the target and offers per-VLAN
Skip/Overwrite with the port grid disabling itself when Skip is active.
Step 3 shows the full plan before a single apply call executes all
operations over one device connection and reports per-VLAN results.

Also fix CPU load display on the Devices page for hardware switches that
report 0% CPU via ASIC offloading — the previous filter (v > 0) silently
dropped all valid zero readings; now filters on field presence instead.

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-backend",
-  "version": "0.10.9-beta",
+  "version": "0.11.0-beta",
   "description": "Mikrotik Network Management Platform - Backend API",
   "main": "dist/index.js",
   "scripts": {