Add settings page for managing forecasting API key and URL via UI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/es-toolkit/dist/predicate/isFile.d.mts

@@ -0,0 +1,22 @@
+//#region src/predicate/isFile.d.ts
+/**
+ * Checks if the given value is a File.
+ *
+ * This function tests whether the provided value is an instance of `File`.
+ * It returns `true` if the value is an instance of `File`, and `false` otherwise.
+ *
+ * @param x - The value to test if it is a File.
+ * @returns True if the value is a File, false otherwise.
+ *
+ * @example
+ * const value1 = new File(["content"], "example.txt");
+ * const value2 = {};
+ * const value3 = new Blob(["content"], { type: "text/plain" });
+ *
+ * console.log(isFile(value1)); // true
+ * console.log(isFile(value2)); // false
+ * console.log(isFile(value3)); // false
+ */
+declare function isFile(x: unknown): x is File;
+//#endregion
+export { isFile };