feat(inline-edit): add WYSIWYG inline dashboard editing mode

Replace the disconnected board edit page with inline editing directly
on the board view. Toggle with Ctrl+E or the Edit button. Features:

- Edit mode store with changeset accumulation and batch save
- Floating toolbar (save, discard, add section, board settings, exit)
- Widget hover overlays with edit/delete/drag controls
- Type-specific widget config panels for all 14 widget types
- Section inline editing (title, icon picker, delete)
- "+" buttons for adding widgets and sections inline
- Section-level drag-and-drop reordering via svelte-dnd-action
- Batch save API endpoint (single Prisma transaction)
- Board properties side panel with live theme/wallpaper preview
- Modal widget type picker with search filtering
- Icon picker component with visual grid and search
- Confirmation dialog modal for all destructive actions
- HTML format support for Note widget (in addition to markdown/text)
- Full i18n support (en + ru) for all new UI strings
- Legacy edit page banner linking to new inline mode

src/lib/components/ui/ConfirmDialog.svelte

@@ -0,0 +1,75 @@
+<script lang="ts">
+	import { t } from 'svelte-i18n';
+	import { fade, scale } from 'svelte/transition';
+
+	interface Props {
+		title: string;
+		message: string;
+		confirmLabel?: string;
+		cancelLabel?: string;
+		destructive?: boolean;
+		onConfirm: () => void;
+		onCancel: () => void;
+	}
+
+	let {
+		title,
+		message,
+		confirmLabel,
+		cancelLabel,
+		destructive = true,
+		onConfirm,
+		onCancel
+	}: Props = $props();
+
+	function handleKeydown(e: KeyboardEvent) {
+		if (e.key === 'Escape') onCancel();
+	}
+</script>
+
+<svelte:window onkeydown={handleKeydown} />
+
+<!-- Backdrop -->
+<div
+	class="fixed inset-0 z-[60] flex items-center justify-center bg-black/30 backdrop-blur-sm"
+	role="button"
+	tabindex="-1"
+	onclick={onCancel}
+	onkeydown={(e) => e.key === 'Enter' && onCancel()}
+	transition:fade={{ duration: 120 }}
+>
+	<!-- Dialog -->
+	<!-- svelte-ignore a11y_click_events_have_key_events -->
+	<!-- svelte-ignore a11y_no_static_element_interactions -->
+	<div
+		class="mx-4 w-full max-w-sm rounded-2xl border border-border bg-card p-6 shadow-2xl"
+		onclick={(e) => e.stopPropagation()}
+		transition:scale={{ start: 0.95, duration: 150 }}
+		role="alertdialog"
+		aria-labelledby="confirm-dialog-title"
+		aria-describedby="confirm-dialog-message"
+	>
+		<h2 id="confirm-dialog-title" class="mb-2 text-base font-semibold text-foreground">{title}</h2>
+		<p id="confirm-dialog-message" class="mb-5 text-sm text-muted-foreground">{message}</p>
+
+		<div class="flex items-center justify-end gap-2">
+			<button
+				type="button"
+				onclick={onCancel}
+				class="rounded-lg border border-border px-4 py-2 text-sm text-foreground transition-colors hover:bg-accent"
+			>
+				{cancelLabel ?? ($t('common.cancel') ?? 'Cancel')}
+			</button>
+			<button
+				type="button"
+				onclick={onConfirm}
+				class="rounded-lg px-4 py-2 text-sm font-medium transition-colors
+					{destructive
+						? 'bg-destructive text-destructive-foreground hover:bg-destructive/90'
+						: 'bg-primary text-primary-foreground hover:bg-primary/90'}"
+			>
+				{confirmLabel ?? ($t('common.delete') ?? 'Delete')}
+			</button>
+		</div>
+	</div>
+</div>