fix(communications,storage): SMS provider field, email status job, Azure folder metric

[kkopanidis]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other (please describe)

Does this PR introduce a breaking change?

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the main branch
• When resolving a specific issue, it's referenced in the PR's description (e.g. fix #xxx, where "xxx" is the issue number)

Summary

• SMS message records always stored provider: 'unknown' even when Twilio, AWS SNS, or MessageBird was configured.

• The BullMQ email status worker still returned a hardcoded SendGrid stub after the communications module migration, so delivery status never reflected the configured ESP.

• Azure storage deleteFolder incremented folders_total instead of decrementing it, unlike every other provider.

• Track the configured SMS provider name on SmsService and persist it on new SmsRecord documents.

• Point the sandboxed status worker at the communications gRPC getEmailStatus path, map responses with the configured transport, and skip status polling for SMTP and Amazon SES.

• Use decrement('folders_total') in Azure deleteFolder.

Test plan

• Configure Twilio SMS, send a message, confirm GET /sms/messages shows provider: twilio
• Configure Mailgun (or SendGrid) email with stored emails enabled, send mail, confirm EmailRecord.status updates after the status job runs
• Confirm SMTP/SES sends do not enqueue an email status job
• On Azure storage, create then delete a folder and confirm folders_total returns to the prior value

Other information: