feat: migrate frontend React 18 → Svelte 5 + SvelteKit

Core logic portable (economy, balance, cosmetics, migrateSave) — zero rewrite.
136 tests green, identiques. Backend inchangé.

- Svelte 5 runes stores (game, auth, toast) remplacent Zustand
- SvelteKit adapter-static SPA (dist/ output, fallback index.html)
- Tailwind v4 conservé, design system .gp-* porté
- Transitions natives : slide, fly, scale, fade sur toute l'UI
- Sidebar tabbée (Production/Evolution/Collection) + CollapsiblePanel
- Mobile bottom sheet avec FAB toggle + backdrop blur
- Click particles réactifs Svelte (plus de DOM impératif)
- TadpoleSprite bounce + glow ring au clic
- Guide refait en accordéon, Achievements avec filtres
- a11y : focus-visible, Escape modals, aria-current, aria-labels
- CI/CD adapté (tests + build + rsync)
- Build 504K (vs ~1.2MB React)

Frontend/src/lib/components/CockpitHeader.svelte

@@ -0,0 +1,29 @@
+<script lang="ts">
+	import { gameStore } from '$lib/stores/game.svelte';
+	import { formatNumber } from '$lib/utils/formatNumber';
+</script>
+
+<div class="gp">
+	<div class="grid grid-cols-5 gap-0.5 px-1">
+		<div class="gp-stat" title="Production automatique par seconde">
+			<span class="gp-label">Prod/s</span>
+			<span class="gp-value gp-accent-green text-[0.8rem]!">{formatNumber(gameStore.productionPerSecond)}</span>
+		</div>
+		<div class="gp-stat" title="Tetards gagnes par clic">
+			<span class="gp-label">/clic</span>
+			<span class="gp-value text-[0.8rem]!">{formatNumber(gameStore.getClickGain())}</span>
+		</div>
+		<div class="gp-stat" title="Multiplicateur global (prestige)">
+			<span class="gp-label">Mult</span>
+			<span class="gp-value text-[0.8rem]!">x{gameStore.state.prestigeMultiplier.toFixed(1)}</span>
+		</div>
+		<div class="gp-stat" title="ADN Ancestral">
+			<span class="gp-label">ADN</span>
+			<span class="gp-value gp-accent-purple text-[0.8rem]!">{gameStore.state.ancestralDna}</span>
+		</div>
+		<div class="gp-stat" title="Nombre de prestiges">
+			<span class="gp-label">Gen.</span>
+			<span class="gp-value text-[0.8rem]!">{gameStore.state.prestigeCount}</span>
+		</div>
+	</div>
+</div>