Add interactive wedding seating planner with drag-and-drop hall layout

[mbil4l]

Motivation

• Replace the terminal landing page with a dedicated interactive wedding seating planner to allow visual assignment of guests to tables in a hall layout.
• Provide a quick demo dataset and UI so planners can try seating assignments immediately without additional setup.

Description

• Replace src/app/page.tsx with a React/TypeScript seating planner that defines Guest and Table types and seeds INITIAL_GUESTS and INITIAL_TABLES.
• Implement drag-and-drop seating behavior and capacity enforcement via assignGuest and per-table onDrop handlers, and expose an + Add Table action via addTable to expand layout dynamically.
• Add reusable UI helpers GuestChip, Zone, and StatCard and a PARTY_COLORS map for per-party styling.
• Render a visual hall map with labeled zones (Stage, Dance Floor, Photo Booth, Buffet), circular table components showing occupancy, and an unassigned waiting area.

Testing

• Ran a production build with npm run build (calls next build), which completed successfully and generated static pages (Compiled successfully and prerendered pages) ✅.
• Attempted npm run lint but the environment triggered Next.js' interactive ESLint setup prompt, so linting could not be completed non-interactively in this run ⚠️.

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Codex Task