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/+page.svelte

@@ -0,0 +1,28 @@
+<script lang="ts">
+	let { data } = $props();
+</script>
+
+<svelte:head>
+	<title>Kanban Board</title>
+</svelte:head>
+
+<div class="flex flex-col items-center justify-center px-4 py-20">
+	<h1 class="text-4xl font-bold text-gray-900 mb-4">Organize your work</h1>
+	<p class="text-lg text-gray-600 mb-8 text-center max-w-xl">
+		A collaborative Kanban board for your team. Create boards, organize tasks, and track progress in real-time.
+	</p>
+	<div class="flex gap-3">
+		<a
+			href="/auth/register"
+			class="rounded-lg bg-[var(--color-primary)] px-6 py-3 text-white font-medium hover:bg-[var(--color-primary-hover)] transition"
+		>
+			Get Started
+		</a>
+		<a
+			href="/boards"
+			class="rounded-lg border border-gray-300 px-6 py-3 text-gray-700 font-medium hover:bg-gray-100 transition"
+		>
+			Browse Boards
+		</a>
+	</div>
+</div>