feat(setup): bootstrap Android plugin and web UI

This initial commit adds a multi-part scaffold for Wechselbild, including a web UI and an Android plugin.
It introduces frontend assets and a package.json-based dev setup, plus plugin scaffolding for Android with Kotlin sources and Cargo.toml for the Tauri plugin.

- Adds Android wallpaper plugin with Kotlin sources and manifest
- Includes web UI scaffold with index.html and package.json
- Adds Tauri plugin scaffold with Cargo.toml and build config

package.json

@@ -0,0 +1,27 @@
+{
+  "name": "wechselbild",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview",
+    "tauri": "tauri"
+  },
+  "dependencies": {
+    "@tauri-apps/api": "^2.8.0",
+    "lucide-react": "^0.468.0",
+    "react": "^19.1.0",
+    "react-dom": "^19.1.0"
+  },
+  "devDependencies": {
+    "@tauri-apps/cli": "^2.8.0",
+    "@types/react": "^19.1.0",
+    "@types/react-dom": "^19.1.0",
+    "@vitejs/plugin-react": "^4.4.1",
+    "playwright": "^1.62.1",
+    "typescript": "~5.8.3",
+    "vite": "^6.3.5"
+  }
+}