build: switch from yarn to npm to manage js dependencies and move js contents to root

yarn v1 is being deprecated and starts to have some issues

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

env.d.ts

@@ -0,0 +1,12 @@
+/// <reference types="histoire/vue" />
+
+/// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  readonly VITE_SERVER_URL: string;
+  readonly VITE_HISTOIRE_ENV: string;
+}
+
+interface ImportMeta {
+  readonly env: ImportMetaEnv;
+}