fix: handle ioerror in imap fetch (#13960)

## Description

The IMAP email fetch job (Inboxes::FetchImapEmailsJob) crashes with an
unhandled IOError: closed stream when the mail server's SSL socket is
closed mid-write during Net::IMAP#fetch. This error was being reported
to Sentry because the rescue clause only caught EOFError, not its parent
class IOError.

Fixes
[CW-6689](https://linear.app/chatwoot/issue/CW-6689/ioerror-closed-stream-ioerror)

Widened the rescue in fetch_imap_emails_job.rb from EOFError to IOError.

In Ruby's exception hierarchy, EOFError is a subclass of IOError:
```
StandardError
  └── IOError
        └── EOFError
```
The Sentry stacktrace shows a plain IOError: closed stream raised from
OpenSSL::Buffering#do_write → Net::IMAP#put_string → Net::IMAP#fetch.
Since this is an IOError (not EOFError), it bypassed the existing rescue
and fell through to the StandardError catch-all, which reported it to
Sentry as an unhandled exception.

Rescuing IOError now catches both:

IOError: closed stream — the reported crash (parent class)
EOFError — the previously handled case (still caught as a subclass)

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)



## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/jobs/inboxes/fetch_imap_emails_job.rb

@@ -13,7 +13,7 @@ class Inboxes::FetchImapEmailsJob < MutexApplicationJob
     end
   rescue *ExceptionList::IMAP_EXCEPTIONS => e
     Rails.logger.error "Authorization error for email channel - #{channel.inbox.id} : #{e.message}"
-  rescue EOFError, OpenSSL::SSL::SSLError, Net::IMAP::NoResponseError, Net::IMAP::BadResponseError, Net::IMAP::InvalidResponseError,
+  rescue IOError, OpenSSL::SSL::SSLError, Net::IMAP::NoResponseError, Net::IMAP::BadResponseError, Net::IMAP::InvalidResponseError,
          Net::IMAP::ResponseParseError, Net::IMAP::ResponseReadError, Net::IMAP::ResponseTooLargeError => e
     Rails.logger.error "Error for email channel - #{channel.inbox.id} : #{e.message}"
   rescue LockAcquisitionError