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/compat/math/sum.d.mts

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+//#region src/compat/math/sum.d.ts
+/**
+ * Computes the sum of the values that are returned by the `iteratee` function.
+ *
+ * It does not coerce values to `number`.
+ *
+ * @param array - The array to iterate over.
+ * @returns Returns the sum.
+ *
+ * @example
+ * sum([1, 2, 3]); // => 6
+ * sum([1n, 2n, 3n]); // => 6n
+ * sum(["1", "2"]); // => "12"
+ * sum([1, undefined, 2]); // => 3
+ * sum(null); // => 0
+ * sum(undefined); // => 0
+ */
+declare function sum(array: ArrayLike<any> | null | undefined): number;
+//#endregion
+export { sum };