feat: UI overhaul - component library + route layouts with instant headers

- Created 11 reusable UI components: PageHeader, SectionCard, StatCard, StatusBadge, TabBar, MemberList, ActivityFeed, EventCard, ContentSkeleton, QuickLinkGrid, ModuleCard
- Created route-specific +layout.svelte for documents, calendar, kanban, events, settings, account
- Each layout renders PageHeader instantly from parent data, shows ContentSkeleton during navigation
- Removed full-page PageSkeleton from parent layout
- Refactored all pages to use new components instead of inline markup
- Overview page: uses StatCard, SectionCard, EventCard, ActivityFeed, MemberList, QuickLinkGrid
- Events list: uses EventCard, Button components
- Event detail: uses ModuleCard, SectionCard
- Settings/Account/Calendar/Kanban: headers in layouts, toolbars in pages
- Added i18n keys for overview page (EN + ET)
- 0 errors, 112 tests pass

src/routes/[orgSlug]/calendar/+page.svelte

@@ -456,13 +456,11 @@
 	<title>Calendar - {data.org.name} | Root</title>
 </svelte:head>
 
-<div class="flex flex-col h-full p-4 lg:p-5 gap-4">
-	<!-- Header -->
-	<header class="flex items-center gap-2 p-1">
-		<h1 class="flex-1 font-heading text-h1 text-white">
-			{m.calendar_title()}
-		</h1>
-		<Button size="md" onclick={() => handleDateClick(new Date())}
+<div class="flex flex-col h-full">
+	<!-- Toolbar -->
+	<div class="flex items-center gap-2 px-6 py-3 border-b border-light/5 shrink-0">
+		<div class="flex-1"></div>
+		<Button size="sm" onclick={() => handleDateClick(new Date())}
 			>{m.btn_new()}</Button
 		>
 		<ContextMenu
@@ -502,10 +500,10 @@
 					: []),
 			]}
 		/>
-	</header>
+	</div>
 
 	<!-- Calendar Grid -->
-	<div class="flex-1 overflow-auto">
+	<div class="flex-1 overflow-auto p-4">
 		<Calendar
 			events={allEvents}
 			onDateClick={handleDateClick}