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>

frontend/src/services/api.ts

@@ -261,7 +261,7 @@ export const devicesApi = {
     api.delete(`/devices/${id}/address-lists/${encodeURIComponent(entryId)}`),
   // Active connections (read-only)
   getConnections: (id: number, limit = 500) =>
-    api.get<{ total: number; connections: Record<string, string>[] }>(`/devices/${id}/connections`, { params: { limit } }),
+    api.get<{ total: number; connections: Record<string, string>[]; tracking: Record<string, string> }>(`/devices/${id}/connections`, { params: { limit } }),
   // Simple queues (bandwidth control)
   getQueues: (id: number) => api.get<Record<string, string>[]>(`/devices/${id}/queues`),
   addQueue: (id: number, data: Record<string, unknown>) =>
@@ -350,6 +350,8 @@ export const clientsApi = {
     client_type?: string;
     limit?: number;
     offset?: number;
+    sort?: string;
+    dir?: 'asc' | 'desc';
   }) =>
     api.get<{ clients: Client[]; total: number }>('/clients', { params }),
   get: (mac: string) => api.get<ClientDetail>(`/clients/${mac}`),