chore: état initial avant refonte (atlas SvelteKit v4.0.0)

Snapshot de l'existant avant application du playbook OKI :
background shader Three.js, carte graphe 3D, timeline statique.

atlas-fediverse/src/lib/components/pages/StepsGrid.svelte

@@ -0,0 +1,84 @@
+<script lang="ts">
+	import Icon, { type IconName } from './Icon.svelte';
+
+	export interface StepItem {
+		step: string;
+		icon: IconName;
+		title: string;
+		description: string;
+	}
+
+	interface Props {
+		items: StepItem[];
+	}
+
+	let { items }: Props = $props();
+</script>
+
+<div class="steps-cq">
+	<ol class="grid" role="list" style:--grid-min="17rem">
+		{#each items as item (item.step)}
+			<li class="step-card">
+				<span class="step-number" aria-hidden="true">{item.step}</span>
+				<span class="step-icon"><Icon name={item.icon} size={24} /></span>
+				<h3>{item.title}</h3>
+				<p>{item.description}</p>
+			</li>
+		{/each}
+	</ol>
+</div>
+
+<style>
+	/* Container query : rythme plus généreux quand le conteneur s'élargit. */
+	.steps-cq {
+		container-type: inline-size;
+	}
+
+	.step-card {
+		display: flex;
+		flex-direction: column;
+		align-items: center;
+		text-align: center;
+		gap: var(--space-3);
+		padding: var(--space-4);
+		background: var(--glass);
+		backdrop-filter: blur(12px);
+		-webkit-backdrop-filter: blur(12px);
+		border: 1px solid var(--glass-border);
+		border-radius: var(--radius-2);
+	}
+
+	.step-number {
+		font-family: var(--font-mono);
+		font-size: var(--text-4);
+		font-weight: 700;
+		line-height: 1;
+		color: color-mix(in oklch, var(--page-accent, var(--accent)) 25%, transparent);
+	}
+
+	.step-icon {
+		display: inline-flex;
+		align-items: center;
+		justify-content: center;
+		inline-size: 3rem;
+		block-size: 3rem;
+		border-radius: var(--radius-1);
+		color: var(--page-accent-text, var(--accent-text));
+		background: color-mix(in oklch, var(--page-accent, var(--accent)) 14%, transparent);
+	}
+
+	h3 {
+		font-size: var(--text-2);
+	}
+
+	p {
+		font-size: var(--text-small);
+		color: var(--ink-soft);
+	}
+
+	@container (min-width: 45rem) {
+		.step-card {
+			padding: var(--space-5);
+		}
+	}
+</style>