feat: enhance Slack notifications with comprehensive data display

[ODORA0]

This PR significantly improves the Slack notification system for better data visibility and user experience.

What I've done

• Increased Row Limit: 5 → 20 rows per Slack message
• Total Row Count: Shows complete dataset size for better context
• Smart Pagination: Handles large datasets gracefully with clear indicators
• Consistent Ordering: Added ORDER BY clause for predictable data display
• Better Formatting: Improved message hierarchy and information structure

Benefits

• Small datasets (≤20 rows): Complete data visibility
• Large datasets (>20 rows): First 20 rows with pagination note
• Better context: Users know exactly how much data exists
• Actionable insights: More informative notifications for decision-making

Technical Changes

• Updated dispatch_to_slack function signature: limit → max_rows_per_message
• Added total row count query before data retrieval
• Implemented conditional pagination messaging
• Enhanced message formatting with clear data hierarchy

Testing

• Tested with small datasets (≤20 rows)
• Verified pagination logic for larger datasets
• Confirmed consistent data ordering
• Validated improved message formatting

Resolves: Limited data visibility in Slack notifications