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/postcss/lib/list.d.ts

@@ -0,0 +1,60 @@
+declare namespace list {
+  type List = {
+    /**
+     * Safely splits comma-separated values (such as those for `transition-*`
+     * and `background` properties).
+     *
+     * ```js
+     * Once (root, { list }) {
+     *   list.comma('black, linear-gradient(white, black)')
+     *   //=> ['black', 'linear-gradient(white, black)']
+     * }
+     * ```
+     *
+     * @param str Comma-separated values.
+     * @return Split values.
+     */
+    comma(str: string): string[]
+
+    default: List
+
+    /**
+     * Safely splits space-separated values (such as those for `background`,
+     * `border-radius`, and other shorthand properties).
+     *
+     * ```js
+     * Once (root, { list }) {
+     *   list.space('1px calc(10% + 1px)') //=> ['1px', 'calc(10% + 1px)']
+     * }
+     * ```
+     *
+     * @param str Space-separated values.
+     * @return Split values.
+     */
+    space(str: string): string[]
+
+    /**
+     * Safely splits values.
+     *
+     * ```js
+     * Once (root, { list }) {
+     *   list.split('1px calc(10% + 1px)', [' ', '\n', '\t']) //=> ['1px', 'calc(10% + 1px)']
+     * }
+     * ```
+     *
+     * @param string separated values.
+     * @param separators array of separators.
+     * @param last boolean indicator.
+     * @return Split values.
+     */
+    split(
+      string: string,
+      separators: readonly string[],
+      last: boolean
+    ): string[]
+  }
+}
+
+declare let list: list.List
+
+export = list