feat #86: add cookie notice

Closes #86 (closed)

frontend/components/cookies.go

+// SPDX-FileCopyrightText: © 2025 Paweł J. Wal <p@steamshard.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package components
+
+import (
+	g "maragu.dev/gomponents"
+	h "maragu.dev/gomponents/html"
+)
+
+func Cookies() g.Node {
+	return h.Div(
+		h.ID("cookies-notice"),
+		h.Class("flex flex-col md:flex-row gap-2 fixed bottom-0 left-0 right-0 bg-white p-4 md:p-2 text-center md:text-left justify-center items-center hidden"),
+		h.P(g.Text("This website uses cookies to keep track of login sessions. By using this website, you agree to the use of cookies.")),
+		h.Button(g.Text("Accept"), g.Attr("type", "button"), g.Attr("class", "bg-blue-500 text-white px-4 py-2 rounded-md"), h.ID("cookies-accept")),
+	)
+}