feat(ui): modern clients pagination + unified syslog page (v0.16.0-beta)

Clients:
- Replace Previous/Next buttons with a "Show N entries" dropdown
  (25/50/100/200, persisted to localStorage) and numbered page selection
  with prev/next chevrons and ellipses for long ranges.

Syslog (Network Services):
- Drop the Single Device / All Devices mode toggle; always show the
  fleet-aggregated view with coverage badges.
- Add a per-section device dropdown + "Add to device" button beside
  "Add to All Devices" for targeting a single device (direct save).
- Edit / enable-disable / remove remain coverage-scoped, so single-device
  management is preserved without the separate mode.

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

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-frontend",
-  "version": "0.15.1-beta",
+  "version": "0.16.0-beta",
   "private": true,
   "type": "module",
   "scripts": {