fix(asyncio): fix error propagation in async request path

Ensure `PubNubAsyncioException` always carries a valid `PNStatus` with error data instead of `None`.

fix(asyncio): fix `PubNubAsyncioException.__str__` crash

Handle cases where status or `error_data` is `None` instead of raising `AttributeError`.

fix(event-engine): fix error type checks in effects

Match `PubNubAsyncioException` which is what `request_future` actually returns on failure.

fix(event-engine): fix give-up logic for unlimited retries

Handle `-1 (unlimited)` correctly since `attempts > -1` was always `true`, causing immediate give-up.

fix(event-engine): initialize heartbeat max retry attempts

Use delay class defaults instead of config value which could be `None` causing `TypeError` on comparison.

fix(event-engine): add missing return after `heartbeat` give-up

Prevent falling through to start a heartbeat after deciding to give up.

fix(request-handlers): use explicit `httpx.Timeout` object

Set all four timeout fields explicitly instead of a 2-tuple that left write and pool unset.

fix(request-handlers): enforce wall-clock deadline to survive system sleep

On macOS and Linux, `time.monotonic()` does not advance during system sleep, causing socket and `asyncio` timeouts (310s subscribe) to stall for hours of wall-clock time. Add `time.time()`-based deadline checks that detect sleep and cancel stale requests within ~5s of wake.

fix(asyncio): replace `asyncio.wait_for` with wall-clock-aware loop

Use `asyncio.wait()` with periodic `time.time()` checks instead of a single monotonic-based `wait_for()`, yielding to the event loop between checks.

fix(native-threads): add `WallClockDeadlineWatchdog`

Persistent single daemon thread monitors `time.time()` every 5s and closes the `httpx` session when the wall-clock deadline passes, interrupting the blocking socket read. Tracks deadlines per calling thread so concurrent requests (e.g., subscribe + publish) don't interfere. Only armed for long-timeout requests (>30s). Session is recreated for subsequent requests

test(wall-clock-deadline): add unit tests for sleep detection

Cover both `asyncio` and threads paths simulated clock jumps, normal passthrough, clean watchdog shutdown, per-thread deadline isolation, concurrent request independence, cleanup, and exception propagation.

test(native-threads): add try/finally cleanup to subscribe tests

Ensure `pubnub.stop()` always runs to prevent non-daemon threads from blocking process exit.

test(native-threads): fix flaky where_now and here_now tests

Enable presence heartbeat and use unique channel names so presence registers on the server.

test(file-upload): fix shared state leak in file upload tests

Restore `cipher_key` after use in `send_file` and pass it explicitly to `download_file`.

test(message-actions): use unique channel names

Avoid collisions with stale data from prior test runs.