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>

.gitignore

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+/tmp
+/out-tsc
+/dist
+
+/node_modules
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+/.pnp
+.pnp.js
+
+.vscode/*