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/isPrimitive.d.mts

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+//#region src/predicate/isPrimitive.d.ts
+/**
+ * Checks whether a value is a JavaScript primitive.
+ * JavaScript primitives include null, undefined, strings, numbers, booleans, symbols, and bigints.
+ *
+ * @param value The value to check.
+ * @returns Returns true if `value` is a primitive, false otherwise.
+ *
+ * @example
+ * isPrimitive(null); // true
+ * isPrimitive(undefined); // true
+ * isPrimitive('123'); // true
+ * isPrimitive(false); // true
+ * isPrimitive(true); // true
+ * isPrimitive(Symbol('a')); // true
+ * isPrimitive(123n); // true
+ * isPrimitive({}); // false
+ * isPrimitive(new Date()); // false
+ * isPrimitive(new Map()); // false
+ * isPrimitive(new Set()); // false
+ * isPrimitive([1, 2, 3]); // false
+ */
+declare function isPrimitive(value: unknown): value is null | undefined | string | number | boolean | symbol | bigint;
+//#endregion
+export { isPrimitive };