feat(webui): bootstrap session handling and login process

pkg/webui/render.go

@@ -0,0 +1,22 @@
+package webui
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"net/http"
+)
+
+func render(w http.ResponseWriter, t *template.Template, status int, data any) {
+	var buf bytes.Buffer
+	if err := t.ExecuteTemplate(&buf, "base.html", data); err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = w.Write([]byte(fmt.Sprintf(
+			"%s: failed to execute template: %+v",
+			http.StatusText(http.StatusInternalServerError),
+			err)))
+	} else {
+		w.WriteHeader(status)
+		_, _ = buf.WriteTo(w)
+	}
+}