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/util/toLength.d.ts

@@ -0,0 +1,20 @@
+//#region src/compat/util/toLength.d.ts
+/**
+ * Converts the value to a valid index. A valid index is an integer that is greater than or equal to `0` and less than or equal to `2^32 - 1`.
+ *
+ * It converts the given value to an integer. If the value is less than `0`, it returns `0`. If the value exceeds `2^32 - 1`, it returns `2^32 - 1`. Values that cannot be converted to a number (such as `NaN` or non-numeric strings) return `0`.
+ *
+ * @param value - The value to convert to a valid index.
+ * @returns The converted value.
+ *
+ * @example
+ * toLength(3.2)  // => 3
+ * toLength(-1)   // => 0
+ * toLength(1.9)  // => 1
+ * toLength('42') // => 42
+ * toLength(null) // => 0
+ * toLength('a')  // => 0
+ */
+declare function toLength(value: any): number;
+//#endregion
+export { toLength };