docs(retry): clarify abort semantics + remove stale circuit-breaker mention

Two doc-only fixes from PR #393 review (Copilot):

1. **bounded-retry.ts BoundedRetryOptions.signal**
   The previous one-line "if aborted, give up immediately" was technically
   correct from the loop's perspective but misleading about what happens
   to an in-flight operation. Expanded to describe the three observation
   points: sleep wakes immediately, in-flight attempt is forwarded the
   per-attempt signal (only truly immediate if the operation itself
   observes it), and the next loop iteration throws BoundedRetryAbortedError.

2. **retry-utils.ts module-level JSDoc**
   The header still listed "Circuit breaker integration" as a feature.
   The circuitBreaker option was removed in commit b531b46999 and the
   withRetry/retryable/RetryManager helpers in 0f2402da58. Updated the
   header to describe the actual current surface (used for Bad MAC
   recovery on decrypt path) and recommend withBoundedRetry for socket
   operations.

Build clean, 35/35 suites, 809/809 tests pass.

Note: not addressing the suppressed comment about removed APIs being a
breaking change — per maintainer policy this fork has a single consumer,
downstream forks absorb on merge.

src/Utils/bounded-retry.ts

@@ -129,7 +129,18 @@ export interface BoundedRetryOptions {
 	shouldRetry?: (err: Error, attempt: number) => boolean
 	/** Hook fired before each retry */
 	onRetry?: (err: Error, attempt: number, delayMs: number) => void
-	/** AbortSignal — if aborted, give up immediately */
+	/**
+	 * AbortSignal — when fired, the loop stops at the next observation point:
+	 *   - If the loop is sleeping between retries, the sleep rejects immediately.
+	 *   - If an attempt is in flight, the abort is forwarded to the operation
+	 *     via the per-attempt signal. The operation must ITSELF observe the
+	 *     signal (e.g. `(signal) => fetch({ signal })`) for cancellation to
+	 *     be truly immediate; otherwise it cancels at the next per-attempt
+	 *     timeout boundary.
+	 *   - Either way, on the next loop iteration BoundedRetryAbortedError is
+	 *     thrown, so the caller never sees more than one trailing attempt
+	 *     after the abort.
+	 */
 	signal?: AbortSignal
 	/** Optional logger for structured retry/give-up/recovery logs */
 	logger?: ILogger

src/Utils/retry-utils.ts

@@ -6,9 +6,17 @@
  * - Jitter to avoid thundering herd
  * - Configurable max attempts
  * - Customizable retry predicates
- * - Circuit breaker integration
- * - Event hooks
- * - Cancellation support
+ * - Cancellation support (AbortSignal)
+ *
+ * Used by `decode-wa-message.ts` for Bad MAC retry recovery on the decrypt
+ * path. For socket-operation retries (uploadPreKeys etc.) prefer
+ * `withBoundedRetry` from `./bounded-retry.ts`, which is empirically
+ * aligned with WhatsApp Android's per-operation backoff.
+ *
+ * NOTE: the previous `circuitBreaker` integration option, the `withRetry`
+ * decorator, the `retryable` wrapper and the `RetryManager` class were
+ * removed when the socket-level circuit breaker was retired — see PR #393
+ * for the rationale.
  *
  * @module Utils/retry-utils
  */