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>

scripts/gen-icons.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd "$(dirname "$0")/../public"
+
+rsvg-convert -w 512 -h 512 icon.svg -o pwa-512x512.png
+rsvg-convert -w 192 -h 192 icon.svg -o pwa-192x192.png
+rsvg-convert -w 180 -h 180 icon.svg -o apple-touch-icon.png
+rsvg-convert -w 32  -h 32  icon.svg -o favicon-32.png
+magick favicon-32.png favicon.ico
+rm favicon-32.png
+
+echo "Icons generated."