feat: backporting existing raylib-cs examples and new official raylib examples to WASM, adopting raylib's original code style

Examples/IExample.cs

@@ -0,0 +1,55 @@
+namespace Examples;
+
+/// <summary>
+/// A runnable raylib example. Loop-spanning state lives in instance fields, (re)initialized in
+/// <see cref="Init"/> so re-selecting an example resets it.
+///
+/// <para>
+/// Desktop drives examples via <c>Program.cs</c> (each also keeps a thin standalone
+/// <c>static Main()</c>); in the browser, <c>Web/Host.cs</c> owns the single window and calls
+/// <see cref="Update"/> one frame at a time from JavaScript. Platform divergences are guarded
+/// with <c>#if BROWSER</c>, preferably around a single constant.
+/// </para>
+/// </summary>
+public interface IExample
+{
+    /// <summary>Display name shown in the navigation dropdown.</summary>
+    string Name { get; }
+
+    /// <summary>Window title, matching the example's standalone <c>Main()</c>.</summary>
+    string Title { get; }
+
+    /// <summary>Desktop window size, matching the standalone <c>Main()</c>. The browser canvas is fixed at 800x450.</summary>
+    int Width => 800;
+
+    /// <inheritdoc cref="Width"/>
+    int Height => 450;
+
+    /// <summary>Config flags the desktop runner applies before window creation. Ignored in the browser.</summary>
+    ConfigFlags ConfigFlags => 0;
+
+    /// <summary>Target FPS. The desktop runner always applies it; the browser host paces its frame loop with it.</summary>
+    int TargetFps => 60;
+
+    /// <summary>Whether the desktop runner disables the cursor. Ignored in the browser (the pointer stays visible).</summary>
+    bool CursorDisabled => false;
+
+    /// <summary>Whether the desktop runner hides the cursor. Ignored in the browser.</summary>
+    bool CursorHidden => false;
+
+    /// <summary>
+    /// Whether the desktop runner should exit its frame loop; defaults to
+    /// <see cref="Raylib.WindowShouldClose"/>. Examples that intercept the close request
+    /// override this and poll WindowShouldClose in <see cref="Update"/> themselves.
+    /// </summary>
+    bool ShouldClose => WindowShouldClose();
+
+    /// <summary>Set up the Example and preload necessary resources.</summary>
+    void Init();
+
+    /// <summary>Render one frame, including BeginDrawing/EndDrawing.</summary>
+    void Update();
+
+    /// <summary>Free resources.</summary>
+    void Unload();
+}