feat: Convert website from static HTML to .NET 9.0 Blazor Web App

Major architectural upgrade from static HTML site to modern Blazor Web App:

- Migrated to .NET 9.0 Blazor Web App framework
- Converted home page with 4 gateway cards (Help Desk, App Store, Cloud, SDK)
- Added new SDK card linking to comprehensive SDK documentation
- Converted SDK documentation page to Blazor component
- Updated template download links to nuget.silverlabs.uk repository
- Implemented multi-stage Docker build with .NET SDK 9.0
- Created Blazor-optimized nginx configuration
- Preserved all original styling and animations
- Added .gitignore for Blazor build artifacts

Technical changes:
- New BlazorApp/ project structure with Components architecture
- MainLayout simplified (no default navigation)
- CSS ported to wwwroot (styles.css + sdk-styles.css)
- Multi-stage Dockerfile: Build with dotnet SDK, serve with nginx
- GitLab CI/CD pipeline compatible (auto-detects new Dockerfile)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

BlazorApp/Components/Pages/Weather.razor

@@ -0,0 +1,64 @@
+@page "/weather"
+@attribute [StreamRendering]
+
+<PageTitle>Weather</PageTitle>
+
+<h1>Weather</h1>
+
+<p>This component demonstrates showing data.</p>
+
+@if (forecasts == null)
+{
+    <p><em>Loading...</em></p>
+}
+else
+{
+    <table class="table">
+        <thead>
+            <tr>
+                <th>Date</th>
+                <th aria-label="Temperature in Celsius">Temp. (C)</th>
+                <th aria-label="Temperature in Farenheit">Temp. (F)</th>
+                <th>Summary</th>
+            </tr>
+        </thead>
+        <tbody>
+            @foreach (var forecast in forecasts)
+            {
+                <tr>
+                    <td>@forecast.Date.ToShortDateString()</td>
+                    <td>@forecast.TemperatureC</td>
+                    <td>@forecast.TemperatureF</td>
+                    <td>@forecast.Summary</td>
+                </tr>
+            }
+        </tbody>
+    </table>
+}
+
+@code {
+    private WeatherForecast[]? forecasts;
+
+    protected override async Task OnInitializedAsync()
+    {
+        // Simulate asynchronous loading to demonstrate streaming rendering
+        await Task.Delay(500);
+
+        var startDate = DateOnly.FromDateTime(DateTime.Now);
+        var summaries = new[] { "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching" };
+        forecasts = Enumerable.Range(1, 5).Select(index => new WeatherForecast
+        {
+            Date = startDate.AddDays(index),
+            TemperatureC = Random.Shared.Next(-20, 55),
+            Summary = summaries[Random.Shared.Next(summaries.Length)]
+        }).ToArray();
+    }
+
+    private class WeatherForecast
+    {
+        public DateOnly Date { get; set; }
+        public int TemperatureC { get; set; }
+        public string? Summary { get; set; }
+        public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
+    }
+}