Embed React app and add new user authentication interface.

- Integrated a React-based web frontend into the Go server using the `embed` package, serving it from `/`.
- Added build and development scripts utilizing Bun for the React app (`package.json`, `README.md`).
- Enhanced auth interface to support better user experience and permissions (`App.jsx`, CSS updates).
- Refactored `/api/auth/login` to serve React UI, removing hardcoded HTML template.
- Implemented `/api/permissions/` with ACL support for user access management.

app/web.go

@@ -0,0 +1,19 @@
+package app
+
+import (
+	"embed"
+	"io/fs"
+	"net/http"
+)
+
+//go:embed web/dist
+var reactAppFS embed.FS
+
+// GetReactAppFS returns a http.FileSystem from the embedded React app
+func GetReactAppFS() http.FileSystem {
+	webDist, err := fs.Sub(reactAppFS, "web/dist")
+	if err != nil {
+		panic("Failed to load embedded web app: " + err.Error())
+	}
+	return http.FS(webDist)
+}