supabase / supabase-swift / 30290972778

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fix(realtime): make subscribe converge after a failed auto-reconnect (#1146)

* fix(realtime): make subscribe converge after a failed auto-reconnect

Fixes four interacting defects from #1145 that could leave a long-lived
RealtimeClientV2 unable to ever subscribe again after a network outage in
which the single-shot auto-reconnect failed:

- Clear the `sawReconnecting` latch when the connection manager reports
  `.disconnected`. Previously the latch survived a *failed* reconnect, so
  the next successful `connect()` (e.g. from `connectOnSubscribe`) was
  misclassified as a reconnect completion and `rejoinChannels()` cancelled
  the very join that connect was performing, surfacing as
  `CancellationError`.

- Stop manufacturing `Swift.CancellationError` for non-cancellation
  failures in `ChannelStateManager`. Socket connect failures and
  channel-closed-while-joining now throw a typed `SubscribeFailure` that
  participates in the retry ladder alongside timeouts, and a server close
  that aborts an in-flight subscribe surfaces as
  `RealtimeError.channelClosedByServer` instead of `CancellationError`.

- Discriminate `join_ref` when handling `phx_close`: a close belonging to
  a previous incarnation's join on the same topic no longer tears down the
  current subscription (mirrors phoenix.js behavior).

- Skip `phx_leave` and the bounded wait for `phx_close` when unsubscribing
  on a dead socket: the server-side channel died with the connection, the
  leave frame could only be buffered into the *next* connection as a stale
  frame (which the server answers with a close, feeding the stale-close
  problem above), and the wait would stall for the full timeout.

Fixes #1145

* fix(realtime): address review findings on subscribe-convergence fix

- Translate any error from a subscribe aborted by `didReceiveClose()` to
  `RealtimeError.channelClosedByServer`. Depending on how the task
  cancellation is observed, the aborted subscribe could exit with
  `Cancella... (continued)

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