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/object/defaultsDeep.d.ts

@@ -0,0 +1,24 @@
+//#region src/compat/object/defaultsDeep.d.ts
+/**
+ * Recursively assigns default values to an `object`, ensuring that certain properties do not remain `undefined`.
+ * It sets default values for properties that are either `undefined` or inherited from `Object.prototype`.
+ *
+ * Similar to `defaults` but recursively applies default values to nested objects.
+ * Source objects are applied in order from left to right, and once a property has been assigned a value,
+ * any subsequent values for that property will be ignored.
+ *
+ * Note: This function modifies the first argument, `object`.
+ *
+ * @template T - The type of the object being processed.
+ * @param target - The target object that will receive default values.
+ * @param sources - One or more source objects that specify default values to apply.
+ * @returns The `object` that has been updated with default values from all sources, recursively merging nested objects.
+ *
+ * @example
+ * defaultsDeep({ a: { b: 2 } }, { a: { b: 3, c: 3 }, d: 4 }); // { a: { b: 2, c: 3 }, d: 4 }
+ * defaultsDeep({ a: { b: undefined } }, { a: { b: 1 } }); // { a: { b: 1 } }
+ * defaultsDeep({ a: null }, { a: { b: 1 } }); // { a: null }
+ */
+declare function defaultsDeep(target: any, ...sources: any[]): any;
+//#endregion
+export { defaultsDeep };