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/loose-envify/loose-envify.js

@@ -0,0 +1,36 @@
+'use strict';
+
+var stream = require('stream');
+var util = require('util');
+var replace = require('./replace');
+
+var jsonExtRe = /\.json$/;
+
+module.exports = function(rootEnv) {
+  rootEnv = rootEnv || process.env;
+  return function (file, trOpts) {
+    if (jsonExtRe.test(file)) {
+      return stream.PassThrough();
+    }
+    var envs = trOpts ? [rootEnv, trOpts] : [rootEnv];
+    return new LooseEnvify(envs);
+  };
+};
+
+function LooseEnvify(envs) {
+  stream.Transform.call(this);
+  this._data = '';
+  this._envs = envs;
+}
+util.inherits(LooseEnvify, stream.Transform);
+
+LooseEnvify.prototype._transform = function(buf, enc, cb) {
+  this._data += buf;
+  cb();
+};
+
+LooseEnvify.prototype._flush = function(cb) {
+  var replaced = replace(this._data, this._envs);
+  this.push(replaced);
+  cb();
+};