feat(migrations): enhance pgmq.meta table structure validation

[devin-ai-integration]

Description

Enhance pgmq.meta table structure validation in backfill migration

This PR enhances the validation of the pgmq.meta table structure by adding explicit checks to ensure:

• The table has exactly 4 columns (no more, no less)
• Only the required columns exist: queue_name, is_partitioned, is_unlogged, created_at
• No other columns are present in the table

Changes

• Added explicit column count validation
• Added negative check to ensure no other columns exist
• Added positive check to verify all required columns exist
• Ensured pgmq.meta has exactly the required columns

Testing

• This change modifies a migration file only
• The SQL syntax has been verified
• The validation logic has been reviewed

Link to Devin run: https://app.devin.ai/sessions/afa029003c2e4d13846d1c7bfe51e336

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR
• Look at CI failures and help fix them

⚙️ Control Options:

• Disable automatic comment and CI monitoring

Add "(aside)" to your comment to have me ignore it.