refactor: update logo and remove unused documentation files

- Replaced the favicon with a new logo in the Astro configuration.
- Deleted outdated documentation files related to Angular tutorials in German and French, including API server and task management sections.
- Adjusted global CSS variables for improved theme consistency.

Author: geromegrignon

astro.config.mjs

@@ -13,7 +13,7 @@ export default defineConfig({
       title: "Angular Tutorials",
       favicon: "/public/favicon.svg",
       logo: {
-        src: "/public/favicon.svg",
+        src: "/public/logo.png",
       },
       social: [
         {
@@ -240,12 +240,6 @@ export default defineConfig({
         en: {
           label: "English",
         },
-        fr: {
-          label: "Français",
-        },
-        de: {
-          label: "Deutsch",
-        },
       },
     }),
     react(),