feat(decks): Edit-Icon auf Deck-Karten + Deck-Edit-Page

- DeckStack: Pencil-Icon absolut unten-rechts, erscheint beim Hover
  (z-index über Card, ausserhalb des <a>-Links zur Detail-Page)
- Neuer Route /decks/[id]/edit: Form für Name, Beschreibung, Farbe
- i18n deck_edit keys (de + en)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/lib/components/DeckStack.svelte

@@ -5,6 +5,7 @@
 	import { t, tn } from '$lib/i18n/index.svelte.ts';
 	import CardSurface from './CardSurface.svelte';
 	import DeckCategoryIcon from './DeckCategoryIcon.svelte';
+	import { PencilSimple } from '@mana/shared-icons';
 
 	interface Props {
 		deck: Deck;
@@ -43,6 +44,16 @@
 		{/each}
 	{/if}
 
+	<a
+		href="/decks/{deck.id}/edit"
+		class="edit-btn"
+		onclick={(e) => e.stopPropagation()}
+		aria-label="Deck bearbeiten"
+		title="Deck bearbeiten"
+	>
+		<PencilSimple size={13} weight="bold" />
+	</a>
+
 	<CardSurface
 		size="md"
 		as={href ? 'a' : 'button'}
@@ -170,4 +181,34 @@
 		border-style: dashed;
 		background: transparent;
 	}
+
+	.edit-btn {
+		position: absolute;
+		bottom: 0.625rem;
+		right: 0.625rem;
+		z-index: 10;
+		width: 1.625rem;
+		height: 1.625rem;
+		border-radius: 0.375rem;
+		background: hsl(var(--color-surface) / 0.92);
+		border: 1px solid hsl(var(--color-border));
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		color: hsl(var(--color-muted-foreground));
+		text-decoration: none;
+		opacity: 0;
+		transition: opacity 0.15s, color 0.12s, background 0.12s, border-color 0.12s;
+		backdrop-filter: blur(4px);
+	}
+
+	.stack-wrap:hover .edit-btn {
+		opacity: 1;
+	}
+
+	.edit-btn:hover {
+		color: hsl(var(--color-foreground));
+		background: hsl(var(--color-surface));
+		border-color: hsl(var(--color-primary) / 0.5);
+	}
 </style>