feat: add static file serving for APK downloads and new files folder

- Add MIME type mapping for .apk files to allow proper download
- Configure static file serving for new "files" directory at /files endpoint
- Enable serving APK and other downloadable files from dedicated folder

src/GreenHome.Api/Program.cs

@@ -127,7 +127,9 @@ void ConfigureStaticFiles(WebApplication app)
 {
     var provider = new FileExtensionContentTypeProvider();
     provider.Mappings[".amr"] = "audio/amr";
+    provider.Mappings[".apk"] = "application/vnd.android.package-archive";
 
+    // Serve existing My_StaticFiles folder
     app.UseStaticFiles(new StaticFileOptions
     {
         FileProvider = new PhysicalFileProvider(
@@ -135,4 +137,13 @@ void ConfigureStaticFiles(WebApplication app)
         RequestPath = "/My_StaticFiles",
         ContentTypeProvider = provider
     });
+
+    // Serve new files folder for APK and other downloads
+    app.UseStaticFiles(new StaticFileOptions
+    {
+        FileProvider = new PhysicalFileProvider(
+            Path.Combine(app.Environment.ContentRootPath, "files")),
+        RequestPath = "/files",
+        ContentTypeProvider = provider
+    });
 }