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>

server.js

@@ -0,0 +1,46 @@
+import express from 'express';
+import { createServer } from 'http';
+import { Server } from 'socket.io';
+import { handler } from './build/handler.js';
+
+const app = express();
+const server = createServer(app);
+
+const io = new Server(server, {
+	cors: {
+		origin: process.env.ORIGIN || 'http://localhost:3000',
+		credentials: true
+	}
+});
+
+// Socket.IO auth + room management
+io.on('connection', (socket) => {
+	console.log(`Socket connected: ${socket.id}`);
+
+	socket.on('join-board', (boardId) => {
+		socket.join(`board:${boardId}`);
+		socket.to(`board:${boardId}`).emit('user-joined', { socketId: socket.id });
+	});
+
+	socket.on('leave-board', (boardId) => {
+		socket.leave(`board:${boardId}`);
+		socket.to(`board:${boardId}`).emit('user-left', { socketId: socket.id });
+	});
+
+	socket.on('disconnect', () => {
+		console.log(`Socket disconnected: ${socket.id}`);
+	});
+});
+
+// Store io globally so it can be accessed if needed
+globalThis.__socketIO = io;
+
+// SvelteKit handler
+app.use(handler);
+
+const port = process.env.PORT || 3000;
+const host = process.env.HOST || '0.0.0.0';
+
+server.listen(port, host, () => {
+	console.log(`Server running on http://${host}:${port}`);
+});