Refactor: Bootstrap 5.3.8, Bootstrap Icons, Client/Http/Configuration layout

- Update Bootstrap to 5.3.8, add Bootstrap Icons; replace custom SVGs
- Fix settings modal: load editing state only when modal opens (avoid refresh overwrite)
- Home: StatusSection and LogsSection components with own timers
- Move HTTP clients under Client/Http with Abstractions namespace pattern
- Rename Options to Configuration; remove empty Options dir
- Components: Modals/, Home/; consistent Abstractions (Services, Client.Services, Client.Http)

src/DnsmasqWebUI/Client/Http/LeasesClient.cs

@@ -0,0 +1,16 @@
+using DnsmasqWebUI.Client.Http.Abstractions;
+using DnsmasqWebUI.Models;
+using System.Net.Http.Json;
+
+namespace DnsmasqWebUI.Client.Http;
+
+public sealed class LeasesClient : ILeasesClient
+{
+    private readonly HttpClient _http;
+
+    public LeasesClient(HttpClient http) => _http = http;
+
+    public async Task<LeasesResult> GetLeasesAsync(CancellationToken ct = default) =>
+        await _http.GetFromJsonAsync<LeasesResult>("api/leases", ct)
+            ?? throw new InvalidOperationException("Unexpected null from api/leases.");
+}