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/map/countBy.js

@@ -0,0 +1,43 @@
+//#region src/map/countBy.ts
+/**
+* Counts the occurrences of items in a Map based on a transformation function.
+*
+* This function takes a Map and a function that generates a key from each value-key pair.
+* It returns an object with the generated keys as properties and their counts as values.
+* The count is incremented for each entry for which the transformation produces the same key.
+*
+* @template K - The type of the Map's keys.
+* @template V - The type of the Map's values.
+* @template K2 - The type of keys produced by the transformation function.
+* @param map - The Map to count occurrences from.
+* @param mapper - The function to produce a key for counting.
+* @returns An object containing the mapped keys and their counts.
+*
+* @example
+* const map = new Map([
+*   ['a', 1],
+*   ['b', 2],
+*   ['c', 1]
+* ]);
+* const result = countBy(map, (value) => value);
+* // result will be { 1: 2, 2: 1 }
+*
+* @example
+* const map = new Map([
+*   ['alice', 20],
+*   ['bob', 30],
+*   ['carol', 20]
+* ]);
+* const result = countBy(map, (value, key) => key[0]);
+* // result will be { a: 1, b: 1, c: 1 }
+*/
+function countBy(map, mapper) {
+	const result = /* @__PURE__ */ new Map();
+	for (const [key, value] of map) {
+		const mappedKey = mapper(value, key, map);
+		result.set(mappedKey, (result.get(mappedKey) ?? 0) + 1);
+	}
+	return result;
+}
+//#endregion
+exports.countBy = countBy;