Add barcode-detector-api-polyfill dependency and update environment variable declarations in SvelteKit project

node_modules/@zxing/text-encoding/esm/encoding/encoding-indexes-provider.d.ts

@@ -0,0 +1,4 @@
+export declare type EncodingIndexMap = {
+    [x: string]: number[];
+};
+export declare function getEncodingIndexes(): EncodingIndexMap;