feat(frontend): regroup settings dialog, icon renderer tiles

Settings splits into labelled sections — renderer, appearance, wallpaper
and CSS, notifications, auth, backup — each with an icon header. Renderer
options gain a per-style glyph and accent-highlighted selection; theme
becomes a segmented Dark/Light control; the dialog widens to max-w-xl.

Renderer switching itself verified working end-to-end (live switch +
persistence across reload); unchanged code path since v2.0.0.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/src/renderers/index.ts

@@ -1,3 +1,4 @@
+import { LayoutGrid, LayoutList, Newspaper, SquareTerminal, type LucideIcon } from "lucide-react";
 import { bento } from "./bento";
 import { cards } from "./cards";
 import { editorial } from "./editorial";
@@ -27,3 +28,10 @@ export const rendererDescriptions: Record<RendererName, string> = {
 	index: "editorial list · masthead",
 	console: "terminal panels · mono",
 };
+
+export const rendererIcons: Record<RendererName, LucideIcon> = {
+	bento: LayoutGrid,
+	cards: LayoutList,
+	index: Newspaper,
+	console: SquareTerminal,
+};