[Feat] Wait for connections to establish before callback, retry on fail

* Delay onConnect until connection is likely established using a timer (7x conn interval), with early completion on peer activity.
* Suppress onDisconnect for 0x3e and route terminal 0x3e failures to onConnectFail.
* Add configurable 0x3e reconnect attempts via `setConnectRetries` or client config (default 2).
* Retry logic suppresses callbacks while retrying; callbacks fire only on final outcome.
* Refactor connect-start path into a shared helper used by initial connect and retries.

Author: h2zero