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/promise/mutex.d.mts

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+//#region src/promise/mutex.d.ts
+/**
+ * A Mutex (mutual exclusion lock) for async functions.
+ * It allows only one async task to access a critical section at a time.
+ *
+ * @example
+ * const mutex = new Mutex();
+ *
+ * async function criticalSection() {
+ *   await mutex.acquire();
+ *   try {
+ *     // This code section cannot be executed simultaneously
+ *   } finally {
+ *     mutex.release();
+ *   }
+ * }
+ *
+ * criticalSection();
+ * criticalSection(); // This call will wait until the first call releases the mutex.
+ */
+declare class Mutex {
+  private semaphore;
+  /**
+   * Checks if the mutex is currently locked.
+   * @returns True if the mutex is locked, false otherwise.
+   *
+   * @example
+   * const mutex = new Mutex();
+   * console.log(mutex.isLocked); // false
+   * await mutex.acquire();
+   * console.log(mutex.isLocked); // true
+   * mutex.release();
+   * console.log(mutex.isLocked); // false
+   */
+  get isLocked(): boolean;
+  /**
+   * Acquires the mutex, blocking if necessary until it is available.
+   * @returns A promise that resolves when the mutex is acquired.
+   *
+   * @example
+   * const mutex = new Mutex();
+   * await mutex.acquire();
+   * try {
+   *   // This code section cannot be executed simultaneously
+   * } finally {
+   *   mutex.release();
+   * }
+   */
+  acquire(): Promise<void>;
+  /**
+   * Releases the mutex, allowing another waiting task to proceed.
+   *
+   * @example
+   * const mutex = new Mutex();
+   * await mutex.acquire();
+   * try {
+   *   // This code section cannot be executed simultaneously
+   * } finally {
+   *   mutex.release(); // Allows another waiting task to proceed.
+   * }
+   */
+  release(): void;
+}
+//#endregion
+export { Mutex };