Initialize Black 7 PWA with React, Vite, and app icons

Sets up Vite + React + TypeScript with vite-plugin-pwa for offline support.
Adds app icon (line-drawn 7 on black) in all required sizes with a generation script.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

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+# Black 7
+
+Scoring app for the card game **Last Panther**, hosted at black7.org.
+
+## What this is
+
+A mobile-first progressive web app (PWA) built with React and TypeScript. No backend — everything runs in the browser. Players use it to track scores during a game of Last Panther.
+
+## Tech stack
+
+- React (UI)
+- TypeScript (strict mode)
+- PWA (installable, offline-capable)
+- No server, no API — browser-only
+
+## Key constraints
+
+- **Mobile-first**: design and test for phone-sized screens first; desktop is secondary
+- **No backend**: all state lives in the browser (localStorage, sessionStorage, or in-memory)
+- **Installable**: must meet PWA requirements (manifest, service worker, HTTPS)
+
+## Running the app
+
+```
+npm install
+npm run dev       # start dev server
+npm run build     # production build
+```
+
+## Project conventions
+
+- Components live in `src/components/`
+- Game logic (scoring rules, state) lives in `src/game/`
+- Types shared across the app live in `src/types.ts`
+- Prefer small, focused components; keep game logic out of UI components
+- No unnecessary comments — name things clearly instead