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>

vite.config.ts

@@ -0,0 +1,23 @@
+import { sveltekit } from '@sveltejs/kit/vite';
+import tailwindcss from '@tailwindcss/vite';
+import { defineConfig } from 'vite';
+import type { Plugin } from 'vite';
+
+function socketIOPlugin(): Plugin {
+	return {
+		name: 'socket-io-dev',
+		configureServer(server) {
+			if (!server.httpServer) return;
+
+			// Dynamic import to avoid bundling socket.io in client
+			import('./src/socket/index.js').then(({ initSocketIO }) => {
+				initSocketIO(server.httpServer!);
+				console.log('Socket.IO dev server initialized');
+			});
+		}
+	};
+}
+
+export default defineConfig({
+	plugins: [tailwindcss(), sveltekit(), socketIOPlugin()]
+});