fix: close pubsub connection on Subscribe error in CancelationPubSub

[Bahtya]

Problem

Fixes #1095

When CancelationPubSub() in internal/rdb/rdb.go calls redis.Subscribe followed by Receive(), and Receive() fails, the pubsub object is not closed before returning the error. This causes a Redis connection leak.

The subscriber goroutine (subscriber.go) retries in an infinite loop on error, so each failed iteration leaks a new Redis connection. Over time, this exhausts the connection pool.

Fix

Add pubsub.Close() before the error return in CancelationPubSub():

pubsub := r.client.Subscribe(ctx, base.CancelChannel)
_, err := pubsub.Receive(ctx)
if err != nil {
    pubsub.Close()  // <-- added: prevent connection leak
    return nil, errors.E(op, errors.Unknown, fmt.Sprintf("redis pubsub receive error: %v", err))
}

This is a minimal, targeted fix that ensures the pubsub connection is always cleaned up when Receive() fails.

Testing

• go build ./... passes
• go vet ./internal/rdb/ passes
• Integration tests requiring a Redis server cannot be run in this environment, but the change is straightforward and equivalent to the cleanup already done on the success path

---

This PR was created by an AI contributor. The fix has been verified with build and vet checks.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 63.32%. Comparing base (2fd155e) to head (dd3c923).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/rdb/rdb.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1104      +/-   ##
==========================================
- Coverage   63.34%   63.32%   -0.02%     
==========================================
  Files          29       29              
  Lines        4984     4985       +1     
==========================================
  Hits         3157     3157              
- Misses       1549     1550       +1     
  Partials      278      278              

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[Bahtya]

Friendly ping on this PR. The fix correctly closes the pubsub connection in the Subscribe error path to prevent connection leaks. The codecov report notes 1 line is missing test coverage — I can add a test case for the error path in CancelationPubSub if that would help move this forward. Please let me know!