Restructure into feature folders with code-behind and scoped CSS

Elternbeirat.Web/Features/Pages/ContentPage.razor

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+@page "/{Slug}"
+@inject PageService PageService
+
+@if (_page is null)
+{
+    <PageTitle>Nicht gefunden</PageTitle>
+}
+else
+{
+    <PageTitle>@_page.Title</PageTitle>
+    <article>
+        @((MarkupString)_page.ContentHtml)
+    </article>
+}

Elternbeirat.Web/Features/Pages/ContentPage.razor.cs

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+using Elternbeirat.Web.Services;
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Http;
+
+namespace Elternbeirat.Web.Features.Pages;
+
+public partial class ContentPage
+{
+    [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; }
+}

Elternbeirat.Web/Features/Pages/Page.cs

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+namespace Elternbeirat.Web.Services;
+
+/// <summary>
+/// A static content page, read from a Markdown file in <c>Content/pages/</c>.
+/// The file name (without extension) is the slug.
+/// </summary>
+public sealed class Page
+{
+    /// <summary>
+    /// URL identifier of the page, taken from the file name without umlauts
+    /// (e.g. <c>vorstandsteam</c>). It appears in the route <c>/{slug}</c>.
+    /// </summary>
+    public required string Slug { get; init; }
+
+    /// <summary>
+    /// Display title from the YAML front matter (<c>titel:</c>). Falls back to
+    /// the slug when no title is set.
+    /// </summary>
+    public required string Title { get; init; }
+
+    /// <summary>
+    /// The page body rendered from Markdown to HTML (front matter excluded).
+    /// </summary>
+    public required string ContentHtml { get; init; }
+}

Elternbeirat.Web/Features/Pages/PageService.cs

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+using Markdig;
+
+namespace Elternbeirat.Web.Services;
+
+/// <summary>
+/// Reads the static content pages from <c>Content/pages/*.md</c>, renders them
+/// to HTML once at startup and keeps them in memory. Registered as a singleton
+/// because the content lives in the image and does not change at runtime.
+/// </summary>
+public sealed class PageService
+{
+    private readonly IReadOnlyDictionary<string, Page> _pagesBySlug;
+
+    /// <summary>
+    /// Reads every Markdown page from the <c>Content/pages</c> directory below
+    /// the application root and caches it.
+    /// </summary>
+    public PageService(IWebHostEnvironment environment)
+    {
+        var pipeline = new MarkdownPipelineBuilder()
+            .UseYamlFrontMatter()
+            .Build();
+
+        var directory = Path.Combine(environment.ContentRootPath, "Content", "pages");
+        var pages = new Dictionary<string, Page>(StringComparer.OrdinalIgnoreCase);
+
+        if (Directory.Exists(directory))
+        {
+            foreach (var path in Directory.EnumerateFiles(directory, "*.md"))
+            {
+                var page = Read(path, pipeline);
+                pages[page.Slug] = page;
+            }
+        }
+
+        _pagesBySlug = pages;
+    }
+
+    /// <summary>
+    /// Returns the page for the given slug, or <c>null</c> if there is none.
+    /// The lookup is case-insensitive.
+    /// </summary>
+    public Page? Find(string slug) =>
+        _pagesBySlug.GetValueOrDefault(slug);
+
+    private static Page Read(string path, MarkdownPipeline pipeline)
+    {
+        var slug = Path.GetFileNameWithoutExtension(path);
+        var source = File.ReadAllText(path);
+
+        var document = Markdown.Parse(source, pipeline);
+        var title = FrontMatter.Read("title", document, source) ?? slug;
+        var html = Markdown.ToHtml(source, pipeline);
+
+        return new Page { Slug = slug, Title = title, ContentHtml = html };
+    }
+}