Switch code, scripts and docs to English; drop plan.md references

Elternbeirat.Web/Components/Pages/ContentPage.razor

@@ -0,0 +1,37 @@
+@page "/{Slug}"
+@using Elternbeirat.Web.Services
+@inject PageService PageService
+
+@if (_page is null)
+{
+    <PageTitle>Nicht gefunden</PageTitle>
+}
+else
+{
+    <PageTitle>@_page.Title</PageTitle>
+    <article>
+        @((MarkupString)_page.ContentHtml)
+    </article>
+}
+
+@code {
+    [Parameter]
+    public string Slug { get; set; } = "";
+
+    private Page? _page;
+
+    protected override void OnParametersSet()
+    {
+        _page = PageService.Find(Slug);
+
+        // Unknown slug -> 404, so UseStatusCodePagesWithReExecute serves the
+        // /not-found page instead of an empty 200 response.
+        if (_page is null && HttpContext is not null)
+        {
+            HttpContext.Response.StatusCode = StatusCodes.Status404NotFound;
+        }
+    }
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
+}