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/predicate/isSafeInteger.d.ts

@@ -0,0 +1,22 @@
+//#region src/compat/predicate/isSafeInteger.d.ts
+/**
+ * Checks if `value` is a safe integer (between -(2^53 – 1) and (2^53 – 1), inclusive).
+ *
+ * A safe integer is an integer that can be precisely represented as a `number` in JavaScript,
+ * without any other integer being rounded to it.
+ *
+ * This function also serves as a type predicate in TypeScript,
+ * narrowing the type of the argument to `number`.
+ *
+ * @param value - The value to check
+ * @returns `true` if `value` is an integer and between the safe values, otherwise `false`
+ *
+ * @example
+ * isSafeInteger(3); // Returns: true
+ * isSafeInteger(Number.MIN_SAFE_INTEGER - 1); // Returns: false
+ * isSafeInteger(1n); // Returns: false
+ * isSafeInteger('1'); // Returns: false
+ */
+declare function isSafeInteger(value: unknown): value is number;
+//#endregion
+export { isSafeInteger };