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/nanoid/non-secure/index.cjs

@@ -0,0 +1,34 @@
+// This alphabet uses `A-Za-z0-9_-` symbols.
+// The order of characters is optimized for better gzip and brotli compression.
+// References to the same file (works both for gzip and brotli):
+// `'use`, `andom`, and `rict'`
+// References to the brotli default dictionary:
+// `-26T`, `1983`, `40px`, `75px`, `bush`, `jack`, `mind`, `very`, and `wolf`
+let urlAlphabet =
+  'useandom-26T198340PX75pxJACKVERYMINDBUSHWOLF_GQZbfghjklqvwyzrict'
+
+let customAlphabet = (alphabet, defaultSize = 21) => {
+  return (size = defaultSize) => {
+    let id = ''
+    // A compact alternative for `for (var i = 0; i < step; i++)`.
+    let i = size | 0
+    while (i--) {
+      // `| 0` is more compact and faster than `Math.floor()`.
+      id += alphabet[(Math.random() * alphabet.length) | 0]
+    }
+    return id
+  }
+}
+
+let nanoid = (size = 21) => {
+  let id = ''
+  // A compact alternative for `for (var i = 0; i < step; i++)`.
+  let i = size | 0
+  while (i--) {
+    // `| 0` is more compact and faster than `Math.floor()`.
+    id += urlAlphabet[(Math.random() * 64) | 0]
+  }
+  return id
+}
+
+module.exports = { nanoid, customAlphabet }