Migrate bos-settings from GTK4 to Tauri + Svelte 5

Ports every remaining view (Keybinds, the last one — dual Flat/MultiLayout
schema detection, per-action dedicated fields with a raw-JSON fallback for
anything not modeled) and removes the now-fully-dead GTK4 crate (root
Cargo.toml + src/), leaving src-tauri/ as the single Rust binary crate.

Also folds in the UX pass done alongside the migration: responsive
multi-column layout instead of a single centered column, chip/dropdown
pickers replacing free-typed fields (Wi-Fi networks, Bar style, keyboard
layout, tag lists), consistent pill-switch toggles and boxed-list card
styling across every page, and a sidebar scroll-chaining fix.

frontend/src/lib/views/Firmware.svelte

@@ -0,0 +1,140 @@
+<script lang="ts">
+	import { onMount } from "svelte";
+	import { invoke } from "@tauri-apps/api/core";
+	import { runStreamingCommand } from "$lib/streaming";
+	import ViewScaffold from "$lib/components/ViewScaffold.svelte";
+	import Group from "$lib/components/Group.svelte";
+	import Hint from "$lib/components/Hint.svelte";
+	import EmptyState from "$lib/components/EmptyState.svelte";
+	import LogView from "$lib/components/LogView.svelte";
+	import RefreshCw from "@lucide/svelte/icons/refresh-cw";
+
+	interface FwDevice {
+		name: string;
+		version: string;
+	}
+
+	let devices = $state<FwDevice[] | null>(null);
+	let log = $state<string[]>([]);
+	let busy = $state(false);
+
+	async function refresh() {
+		devices = await invoke<FwDevice[]>("get_updatable_firmware");
+	}
+
+	onMount(refresh);
+
+	function appendLine(line: string) {
+		log = [...log, line];
+	}
+
+	async function checkForUpdates() {
+		log = [];
+		busy = true;
+		await runStreamingCommand("fwupdmgr", ["refresh"], appendLine);
+		busy = false;
+		await refresh();
+	}
+
+	async function updateAll() {
+		log = [];
+		busy = true;
+		await runStreamingCommand("fwupdmgr", ["update", "-y"], appendLine);
+		busy = false;
+		await refresh();
+	}
+</script>
+
+<ViewScaffold title="Firmware">
+	<Group
+		title="Updatable devices"
+		hint="Firmware updates for hardware that supports them (UEFI, some peripherals). fwupd-refresh.timer already keeps update metadata current in the background."
+		wide
+	>
+		<div class="list">
+			{#if devices === null}
+				<Hint text="Loading…" />
+			{:else if devices.length === 0}
+				<EmptyState icon={RefreshCw} title="No updatable firmware devices found" hint="Not every device supports firmware updates through fwupd." />
+			{:else}
+				{#each devices as dev (dev.name)}
+					<div class="row">
+						<span class="name" title={dev.name}>{dev.name}</span>
+						<span class="version" title={dev.version}>{dev.version}</span>
+					</div>
+				{/each}
+			{/if}
+		</div>
+
+		<div class="btn-row">
+			<button disabled={busy} onclick={checkForUpdates}>Check for updates</button>
+			<button disabled={busy} class="primary" onclick={updateAll}>Update all</button>
+			<button disabled={busy} onclick={refresh}>Refresh list</button>
+		</div>
+	</Group>
+
+	<LogView lines={log} />
+</ViewScaffold>
+
+<style>
+	.list {
+		max-height: 320px;
+		overflow-y: auto;
+		display: flex;
+		flex-direction: column;
+		gap: 6px;
+	}
+
+	.row {
+		display: flex;
+		align-items: center;
+		gap: var(--space-md, 12px);
+		background-color: var(--surface);
+		border-radius: var(--radius-primary, 8px);
+		padding: var(--space-sm, 8px) var(--space-md, 12px);
+		min-width: 0;
+	}
+
+	.name {
+		flex: 1;
+		min-width: 0;
+		overflow: hidden;
+		text-overflow: ellipsis;
+		white-space: nowrap;
+	}
+
+	.version {
+		opacity: 0.75;
+		font-size: var(--font-size-secondary, 12px);
+		flex-shrink: 0;
+		max-width: 40%;
+		overflow: hidden;
+		text-overflow: ellipsis;
+		white-space: nowrap;
+	}
+
+	.btn-row {
+		display: flex;
+		gap: var(--space-sm, 8px);
+		margin-top: var(--space-sm, 8px);
+	}
+
+	button {
+		background-color: var(--surface);
+		color: var(--on-surface);
+		border: none;
+		border-radius: var(--radius-primary, 8px);
+		padding: var(--space-xs, 4px) var(--space-md, 12px);
+		cursor: pointer;
+	}
+
+	button.primary {
+		background-color: var(--accent);
+		color: var(--on-accent);
+	}
+
+	button:disabled {
+		opacity: 0.5;
+		cursor: default;
+	}
+</style>