feat(cli): Add --dry-run flag to prune command for safer operations

[kariy]

Description:
Currently, the katana db prune command immediately executes database pruning operations which permanently delete historical trie data. This poses a risk for users who might accidentally run the wrong command or want to preview the impact before execution.

Feature Request:
Add a --dry-run flag that:

• Simulates the pruning operation without actually deleting data
• Reports what would be deleted (number of entries, affected tables, estimated space to be reclaimed)
• Shows which blocks would be pruned
• Validates the operation parameters

Example Usage:

# Preview what would be deleted
katana db prune --latest --dry-run -p path/to/db

# Preview keeping last 1000 blocks
katana db prune --keep-last 1000 --dry-run -p path/to/db

Implementation Notes:

• Modify bin/katana/src/cli/db/prune.rs to add the dry-run flag
• Count entries that would be deleted without performing actual deletions
• Display summary statistics after the dry run