refactor: separate podcasts from downloads — own route + nav item

- /podcasts — new page with PodcastPlayer (headphones icon)
- /downloads — old media page renamed (download icon)
- /media — kept for backward compat (same as downloads)
- Nav: Reader → Podcasts → Downloads → Brain

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend-v2/src/lib/components/layout/AppShell.svelte

@@ -7,7 +7,9 @@
 		CalendarDays,
 		CircleDot,
 		Compass,
+		Download,
 		Dumbbell,
+		Headphones,
 		Landmark,
 		LibraryBig,
 		Menu,
@@ -42,7 +44,8 @@
 		{ id: 'budget', href: '/budget', label: 'Budget', icon: Landmark },
 		{ id: 'inventory', href: '/inventory', label: 'Inventory', icon: Package2 },
 		{ id: 'reader', href: '/reader', label: 'Reader', icon: BookOpen },
-		{ id: 'media', href: '/media', label: 'Media', icon: LibraryBig },
+		{ id: 'media', href: '/podcasts', label: 'Podcasts', icon: Headphones },
+		{ id: 'downloads', href: '/downloads', label: 'Downloads', icon: Download },
 		{ id: 'brain', href: '/brain', label: 'Brain', icon: Brain },
 		{ id: 'settings', href: '/settings', label: 'Settings', icon: Settings2 }
 	];