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/string/snakeCase.d.mts

@@ -0,0 +1,18 @@
+//#region src/string/snakeCase.d.ts
+/**
+ * Converts a string to snake case.
+ *
+ * Snake case is the naming convention in which each word is written in lowercase and separated by an underscore (_) character.
+ *
+ * @param str - The string that is to be changed to snake case.
+ * @returns The converted string to snake case.
+ *
+ * @example
+ * const convertedStr1 = snakeCase('camelCase') // returns 'camel_case'
+ * const convertedStr2 = snakeCase('some whitespace') // returns 'some_whitespace'
+ * const convertedStr3 = snakeCase('hyphen-text') // returns 'hyphen_text'
+ * const convertedStr4 = snakeCase('HTTPRequest') // returns 'http_request'
+ */
+declare function snakeCase(str: string): string;
+//#endregion
+export { snakeCase };