feat(phase2): per-board access control UI

- BoardAccessControl component with user/group autocomplete
- BoardShareDialog modal with copy link, guest toggle, quick add
- Board permissions REST API (GET/POST/DELETE)
- Access indicators on BoardCard (lock, globe, shared icons)
- Guest access toggle in board editor with status preview
- Enhanced PermissionEditor with search autocomplete
- i18n translations for all new strings (EN/RU)

src/routes/boards/[boardId]/+page.svelte

@@ -3,8 +3,23 @@
 	import type { PageData } from './$types.js';
 	import Board from '$lib/components/board/Board.svelte';
 	import BoardHeader from '$lib/components/board/BoardHeader.svelte';
+	import BoardShareDialog from '$lib/components/board/BoardShareDialog.svelte';
 
 	let { data }: { data: PageData } = $props();
+
+	let showShareDialog = $state(false);
+
+	async function handleGuestToggle(value: boolean) {
+		try {
+			await fetch(`/api/boards/${data.board.id}`, {
+				method: 'PATCH',
+				headers: { 'Content-Type': 'application/json' },
+				body: JSON.stringify({ isGuestAccessible: value })
+			});
+		} catch (err) {
+			console.error('Failed to update guest access:', err);
+		}
+	}
 </script>
 
 <svelte:head>
@@ -19,8 +34,21 @@
 			icon={data.board.icon}
 			boardId={data.board.id}
 			canEdit={data.canEdit}
+			onShare={() => { showShareDialog = true; }}
 		/>
 
 		<Board sections={data.board.sections} allApps={data.allApps} />
 	</div>
 </div>
+
+{#if showShareDialog && data.canEdit}
+	<BoardShareDialog
+		boardId={data.board.id}
+		boardName={data.board.name}
+		isGuestAccessible={data.board.isGuestAccessible}
+		users={data.users ?? []}
+		groups={data.groups ?? []}
+		onClose={() => { showShareDialog = false; }}
+		onGuestToggle={handleGuestToggle}
+	/>
+{/if}