Add Cookbook S01-S22 (draft)

docs-src/pages/en/cookbook/s04-static-files.md

@@ -0,0 +1,55 @@
+---
+title: "S04. Serve Static Files"
+order: 23
+status: "draft"
+---
+
+To serve static files like HTML, CSS, and images, use `set_mount_point()`. Just map a URL path to a local directory, and the whole directory becomes accessible.
+
+## Basic usage
+
+```cpp
+httplib::Server svr;
+svr.set_mount_point("/", "./public");
+svr.listen("0.0.0.0", 8080);
+```
+
+`./public/index.html` is now reachable at `http://localhost:8080/index.html`, and `./public/css/style.css` at `http://localhost:8080/css/style.css`. The directory layout maps directly to URLs.
+
+## Multiple mount points
+
+You can register more than one mount point.
+
+```cpp
+svr.set_mount_point("/", "./public");
+svr.set_mount_point("/assets", "./dist/assets");
+svr.set_mount_point("/uploads", "./var/uploads");
+```
+
+You can even mount multiple directories at the same path — they're searched in registration order, and the first hit wins.
+
+## Combine with API handlers
+
+Static files and API handlers coexist happily. Handlers registered with `Get()` and friends take priority; the mount points are searched only when nothing matches.
+
+```cpp
+svr.Get("/api/users", [](const auto &req, auto &res) {
+  res.set_content("[]", "application/json");
+});
+
+svr.set_mount_point("/", "./public");
+```
+
+This gives you an SPA-friendly setup: `/api/*` hits the handlers, everything else is served from `./public/`.
+
+## Add MIME types
+
+cpp-httplib ships with a built-in extension-to-Content-Type map, but you can add your own.
+
+```cpp
+svr.set_file_extension_and_mimetype_mapping("wasm", "application/wasm");
+```
+
+> **Warning:** The static file server methods are **not thread-safe**. Don't call them after `listen()` — configure everything before starting the server.
+
+> For download-style responses, see S06. Return a File Download Response.