feat(ui): theme-aware logo, dashboard bar graph, server-side client sorting (v0.14.1-beta)

UI/UX refinements on top of v0.14.0-beta, all validated on the test server:

- Logo: new theme-aware compass iconmark (light/dark SVGs swapped via the
  dark class), sized to 45px; favicon updated to match. Wordmark casing
  corrected to "MikroTik Manager" (font size unchanged).
- Navigation icons enlarged 15 -> 17px.
- Dashboard: "Connected clients" line chart converted to a bar chart with a
  category axis + light downsampling so bars stay readably thick across ranges.
- Clients: sorting is now server-side across the whole dataset (was sorting
  only the current page, so Type/others appeared to do nothing on a uniform
  page); table uses a fixed column layout + keepPreviousData so columns no
  longer jump or blank out when sorting/paging. Backend clients route gains
  whitelisted sort/dir params (safe numeric IP sort, deterministic tiebreaker).
- Connections tab: surfaces the live /ip/firewall/connection/tracking state
  (on/auto/off pill) and clearer empty-state copy explaining auto-mode.

Lint/typecheck/build/jest green in both workspaces; npm audit --audit-level=high
clean.

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

backend/src/services/mikrotik/DeviceCollector.ts

@@ -1824,6 +1824,13 @@ export class DeviceCollector {
     return this.client.execute('/ip/firewall/connection/print', { detail: '' }).catch(() => [] as Record<string, string>[]);
   }
 
+  // /ip/firewall/connection/tracking holds the global conntrack state. `enabled`
+  // is yes / no / auto (auto = on only once firewall/NAT/mangle rules exist).
+  async getConnectionTracking(): Promise<Record<string, string>> {
+    const rows = await this.client.execute('/ip/firewall/connection/tracking/print', {}).catch(() => [] as Record<string, string>[]);
+    return rows[0] || {};
+  }
+
   // ─── Simple Queues (per-client / per-subnet bandwidth control) ──────────────
 
   async getSimpleQueues(): Promise<Record<string, string>[]> {