feat: enhance drop statement warnings with user confirmation

[kazuooooo]

Summary

• Add stronger warnings and interactive confirmation when DROP statements are detected in schema diffs
• Add --confirm-drops option to control drop warning behavior
• Helps prevent accidental data loss from column renames being detected as DROP+ADD operations

Motivation

Currently, supabase db diff shows a weak warning when DROP statements are detected. This is particularly problematic for column renames, which are detected as DROP COLUMN + ADD COLUMN operations, potentially causing data loss.

Changes

• Show clear danger warning with red highlighting and visual separator
• List all detected DROP statements with red arrows
• Explain specific risks including:
  • Column renames being detected as DROP + ADD
  • Permanent data loss from table/schema deletions
  • Suggestion to use RENAME operations instead
• Require user confirmation with default "No" for safety
• Operation is cancelled if user declines
• NEW: Add --confirm-drops option with three modes:
  • prompt (default): Show interactive confirmation prompt
  • skip: Bypass confirmation and proceed automatically
  • deny: Always refuse operations with DROP statements

Test plan

• Added unit tests for the new showDropWarningAndConfirm function
• Added unit tests for --confirm-drops option handling
• Manual testing with actual DROP operations
• Manual testing with column rename scenarios
• Manual testing with all --confirm-drops modes

Example output

⚠️  DANGEROUS OPERATION DETECTED
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

The following DROP statements were found in your schema diff:

  ▶ ALTER TABLE public.users DROP COLUMN old_name
  ▶ DROP TABLE public.legacy_data

❗ These operations may cause DATA LOSS:
  • Column renames are detected as DROP + ADD, which will lose existing data
  • Table or schema deletions will permanently remove all data
  • Consider using RENAME operations instead of DROP + ADD for columns

Please review the generated migration file carefully before proceeding.

Do you want to continue with this potentially destructive operation? [y/N]

New option usage

# Default behavior (show prompt)
supabase db diff

# Skip confirmation and proceed automatically
supabase db diff --confirm-drops=skip

# Always deny DROP operations
supabase db diff --confirm-drops=deny

🤖 Generated with Claude Code

[kazuooooo]

Sorry, I'm cheking by myself, and reopen.