Initial implementation: multi-tenant Kanban board (Phase 1)

Complete Phase 1 foundation with working board, column, and card CRUD:
- SvelteKit + TypeScript + Tailwind CSS v4 + adapter-node
- Full Prisma schema with 18 tables (tenants, users, boards, columns, cards, etc.)
- Multi-tenant architecture with hostname-based tenant resolution
- Email/password auth with bcrypt + session cookies
- Board/Column/Card API routes with full CRUD
- Fractional indexing for drag-and-drop ordering
- Board view with svelte-dnd-action for column and card drag-and-drop
- Card modal with inline editing
- Auth pages (login, register)
- Board listing with create form
- RLS policies SQL script for tenant isolation
- Prisma RLS client extensions (forTenant/bypassRLS)
- Permission helpers (canEditBoard, canManageMembers, etc.)
- Socket.IO server setup (dev Vite plugin + production Express server)
- Client-side socket store for real-time updates
- Docker Compose (app + PostgreSQL 16) + multi-stage Dockerfile
- Database seed script (default tenant + admin user)

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

src/routes/+layout.svelte

@@ -0,0 +1,54 @@
+<script lang="ts">
+	import '../app.css';
+	import type { Snippet } from 'svelte';
+
+	let { children, data }: { children: Snippet; data: { user: any; tenant: any } } = $props();
+</script>
+
+<div class="min-h-screen bg-gray-50">
+	<nav class="bg-[var(--color-primary)] shadow-sm">
+		<div class="mx-auto max-w-7xl px-4 sm:px-6 lg:px-8">
+			<div class="flex h-14 items-center justify-between">
+				<a href="/" class="flex items-center gap-2 text-white font-bold text-lg">
+					<svg class="w-6 h-6" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+						<rect x="3" y="3" width="7" height="7" rx="1" />
+						<rect x="14" y="3" width="7" height="4" rx="1" />
+						<rect x="14" y="10" width="7" height="7" rx="1" />
+						<rect x="3" y="13" width="7" height="8" rx="1" />
+					</svg>
+					{data.tenant?.name ?? 'Kanban'}
+				</a>
+
+				<div class="flex items-center gap-3">
+					{#if data.user}
+						<span class="text-white/80 text-sm">{data.user.name}</span>
+						<button
+							onclick={async () => {
+								await fetch('/api/auth/logout', { method: 'POST' });
+								window.location.href = '/';
+							}}
+							class="rounded bg-white/20 px-3 py-1.5 text-sm text-white hover:bg-white/30 transition"
+						>
+							Logout
+						</button>
+					{:else}
+						<a
+							href="/auth/login"
+							class="rounded bg-white/20 px-3 py-1.5 text-sm text-white hover:bg-white/30 transition"
+						>
+							Login
+						</a>
+						<a
+							href="/auth/register"
+							class="rounded bg-white px-3 py-1.5 text-sm text-[var(--color-primary)] font-medium hover:bg-white/90 transition"
+						>
+							Register
+						</a>
+					{/if}
+				</div>
+			</div>
+		</div>
+	</nav>
+
+	{@render children()}
+</div>