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/app.d.ts

@@ -0,0 +1,33 @@
+// See https://svelte.dev/docs/kit/types#app.d.ts
+import type { PrismaClient } from '@prisma/client';
+
+declare global {
+	namespace App {
+		interface Error {
+			message: string;
+			code?: string;
+		}
+		interface Locals {
+			tenant: {
+				id: string;
+				name: string;
+				slug: string;
+			} | null;
+			user: {
+				id: string;
+				email: string;
+				name: string;
+				globalRole: string;
+				tenantRole: string | null;
+			} | null;
+			session: {
+				id: string;
+			} | null;
+		}
+		// interface PageData {}
+		// interface PageState {}
+		// interface Platform {}
+	}
+}
+
+export {};