fix(realtime): resolve additional bugs in auth token handling and unsubscribe flow

This commit addresses additional bugs discovered during code review:

**Auth Token Handling Bug:**

1. **setAuth() Token Assignment**
   - Fixed critical bug where wrong variable was assigned to accessToken
   - Was using input parameter `token` instead of computed `tokenToSend`
   - This prevented access token callback from being properly stored
   - Now correctly uses `tokenToSend` which includes callback result

2. **setAuth() Channel Updates**
   - Fixed sending wrong token to channels during auth updates
   - Was sending `token` parameter instead of `tokenToSend`
   - Channels now receive the correct token from callback

**Disconnect Cleanup:**

3. **Missing reconnectTask Cancellation**
   - disconnect() now properly cancels reconnectTask
   - Prevents reconnect attempts during explicit disconnect

**Subscription Improvements:**

4. **Socket Health Check During Retry**
   - Added socket connection verification after retry delay
   - Prevents subscription attempts on disconnected socket
   - Aborts retry loop if socket disconnects during backoff

5. **Unsubscribe Confirmation**
   - unsubscribe() now waits for server acknowledgment
   - Ensures clean channel removal before returning
   - Matches subscribe() behavior of waiting for status change

**Impact:**
- Fixes auth token not being updated when using callback
- Prevents sending stale/incorrect tokens to channels
- Cleaner disconnect and unsubscribe flows
- More robust subscription retry logic

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: grdsdev

Sources/Realtime/RealtimeChannelV2.swift

@@ -138,6 +138,14 @@ public final class RealtimeChannelV2: Sendable, RealtimeChannelProtocol {
 
           do {
             try await _clock.sleep(for: delay)
+
+            // Check if socket is still connected after delay
+            if socket.status != .connected {
+              logger?.debug(
+                "Socket disconnected during retry delay for channel '\(topic)', aborting subscription"
+              )
+              throw CancellationError()
+            }
           } catch {
             // If sleep is cancelled, break out of retry loop
             logger?.debug("Subscription retry cancelled for channel '\(topic)'")
@@ -240,6 +248,9 @@ public final class RealtimeChannelV2: Sendable, RealtimeChannelProtocol {
     logger?.debug("Unsubscribing from channel \(topic)")
 
     await push(ChannelEvent.leave)
+
+    // Wait for server confirmation of unsubscription
+    _ = await statusChange.first { @Sendable in $0 == .unsubscribed }
   }
 
   @available(

Sources/Realtime/RealtimeClientV2.swift

@@ -519,6 +519,7 @@ public final class RealtimeClientV2: Sendable, RealtimeClientProtocol {
       $0.messageTask?.cancel()
       $0.heartbeatTask?.cancel()
       $0.connectionTask?.cancel()
+      $0.reconnectTask?.cancel()
       $0.pendingHeartbeatRef = nil
       $0.sendBuffer = []
       $0.conn = nil
@@ -544,16 +545,16 @@ public final class RealtimeClientV2: Sendable, RealtimeClientProtocol {
       return
     }
 
-    mutableState.withValue { [token] in
-      $0.accessToken = token
+    mutableState.withValue { [tokenToSend] in
+      $0.accessToken = tokenToSend
     }
 
     for channel in channels.values {
       if channel.status == .subscribed {
         options.logger?.debug("Updating auth token for channel \(channel.topic)")
         await channel.push(
           ChannelEvent.accessToken,
-          payload: ["access_token": token.map { .string($0) } ?? .null]
+          payload: ["access_token": tokenToSend.map { .string($0) } ?? .null]
         )
       }
     }