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/async/index.browser.js

@@ -0,0 +1,34 @@
+let random = async bytes => crypto.getRandomValues(new Uint8Array(bytes))
+let customAlphabet = (alphabet, defaultSize = 21) => {
+  let mask = (2 << (Math.log(alphabet.length - 1) / Math.LN2)) - 1
+  let step = -~((1.6 * mask * defaultSize) / alphabet.length)
+  return async (size = defaultSize) => {
+    let id = ''
+    while (true) {
+      let bytes = crypto.getRandomValues(new Uint8Array(step))
+      let i = step | 0
+      while (i--) {
+        id += alphabet[bytes[i] & mask] || ''
+        if (id.length === size) return id
+      }
+    }
+  }
+}
+let nanoid = async (size = 21) => {
+  let id = ''
+  let bytes = crypto.getRandomValues(new Uint8Array((size |= 0)))
+  while (size--) {
+    let byte = bytes[size] & 63
+    if (byte < 36) {
+      id += byte.toString(36)
+    } else if (byte < 62) {
+      id += (byte - 26).toString(36).toUpperCase()
+    } else if (byte < 63) {
+      id += '_'
+    } else {
+      id += '-'
+    }
+  }
+  return id
+}
+export { nanoid, customAlphabet, random }