feat(planner): overhaul desktop layout — flip tiles, no right panel

Replaces 3-panel layout with 2-panel (sidebar + full-width grid):
- Remove persistent right panel and toolbar + Gericht hinzufügen button
- grid-cols-7 tiles use DesktopDayTile (CSS 3D card flip)
- RecipePickerDrawer slides in on tile CTA / Gericht tauschen
- Page-owned activeSlotId + drawerOpen/drawerSlotId state
- Single Escape handler: drawer > flip priority
- Extend server load to forward recipe tags from /v1/recipes API

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

frontend/src/lib/planner/DesktopDayTile.svelte

@@ -35,6 +35,7 @@
 		isPlanner,
 		slotMap,
 		suggestions,
+		topSuggestion,
 		onflip,
 		onclose,
 		onswap,
@@ -47,6 +48,7 @@
 		isPlanner: boolean;
 		slotMap: Record<string, any>;
 		suggestions: Suggestion[];
+		topSuggestion?: Suggestion;
 		onflip?: (slotId: string) => void;
 		onclose?: () => void;
 		onswap?: () => void;
@@ -83,7 +85,7 @@
 
 {#if slot.recipe}
 	<div
-		data-testid="day-meal-card"
+		data-testid="day-meal-card-{slot.slotDate ?? ''}"
 		role="button"
 		tabindex="0"
 		aria-label={slot.recipe?.name ?? 'Gericht'}
@@ -155,7 +157,7 @@
 		slotId={slot.id ?? ''}
 		{isPlanner}
 		{slotMap}
-		topSuggestion={undefined}
+		{topSuggestion}
 		{onaddrecipe}
 	/>
 {/if}