feat: V1 prototype — Vite/React/TS tileset generator

- Scaffold: package.json, tsconfig.json, vite.config.ts, index.html
- src/lib/imageProcessor.ts: full pipeline (normalize, offset, seam repair, export, validation)
- src/components/UploadPanel.tsx: drag-and-drop, file picker, clipboard paste
- src/components/SettingsPanel.tsx: all controls per spec
- src/components/PreviewPanel.tsx: Original / Tileable / Repeated tabs
- src/components/ErrorBanner.tsx: dismissible error/warning banners
- src/App.tsx: root component wiring everything together
- src/index.css: dark premium glassmorphism theme w/ Inter font

node_modules/source-map-js/source-map.js

@@ -0,0 +1,8 @@
+/*
+ * Copyright 2009-2011 Mozilla Foundation and contributors
+ * Licensed under the New BSD license. See LICENSE.txt or:
+ * http://opensource.org/licenses/BSD-3-Clause
+ */
+exports.SourceMapGenerator = require('./lib/source-map-generator').SourceMapGenerator;
+exports.SourceMapConsumer = require('./lib/source-map-consumer').SourceMapConsumer;
+exports.SourceNode = require('./lib/source-node').SourceNode;