Implement Standalone Android App via Flutter WebView

- Configured `vite.config.ts` for relative base path support.
- Initialized `mobile_app` Flutter project with `webview_flutter`.
- Added `assets/www` to Flutter assets configuration.
- Implemented `mobile_app/lib/main.dart` with WebView and Bridge API integration (Water Level Slider).
- Updated `.gitignore` for Flutter artifacts.
- Successfully built APK artifacts.

Co-authored-by: kliffdafunkfacekilla-arch <239708976+kliffdafunkfacekilla-arch@users.noreply.github.com>

mobile_app/assets/www/libs/indexedDB.js

@@ -0,0 +1,65 @@
+let db;
+
+const DATABASE_NAME = "d2";
+const STORE_NAME = "s";
+
+const openDatabase = () => {
+  return new Promise((resolve, reject) => {
+    if (db) resolve();
+
+    if (!window.indexedDB) return reject("IndexedDB is not supported");
+    const request = window.indexedDB.open(DATABASE_NAME);
+
+    request.onsuccess = event => {
+      db = event.target.result;
+      resolve();
+    };
+
+    request.onerror = event => {
+      console.error("IndexedDB request error");
+      reject();
+    };
+
+    request.onupgradeneeded = event => {
+      db = event.target.result;
+      const objectStore = db.createObjectStore(STORE_NAME, {keyPath: "key"});
+      objectStore.transaction.oncomplete = () => {
+        db = event.target.result;
+      };
+    };
+  });
+};
+
+const ldb = {
+  get: key => {
+    return new Promise((resolve, reject) => {
+      openDatabase().then(() => {
+        const hasStore = Array.from(db.objectStoreNames).includes(STORE_NAME);
+        if (!hasStore) return reject("IndexedDB: no store found");
+
+        const transaction = db.transaction(STORE_NAME, "readonly");
+        const objectStore = transaction.objectStore(STORE_NAME);
+        const getRequest = objectStore.get(key);
+
+        getRequest.onsuccess = event => {
+          const result = event.target.result?.value || null;
+          resolve(result);
+        };
+      });
+    });
+  },
+
+  set: (keyName, value) => {
+    return new Promise(resolve => {
+      openDatabase().then(() => {
+        const transaction = db.transaction(STORE_NAME, "readwrite");
+        const objectStore = transaction.objectStore([STORE_NAME]);
+        const putRequest = objectStore.put({key: keyName, value});
+
+        putRequest.onsuccess = () => {
+          resolve();
+        };
+      });
+    });
+  }
+};