[good first issue] Add --verbose flag for detailed scan output

[Carlos-Projects]

Task

Add a --verbose flag to memmark scan that shows detailed progress per pipeline stage.

What to do

• Add --verbose / -v option
• Show which pipeline stage is running and findings per stage
• Use Rich for formatted output

Acceptance criteria

• memmark scan memory.json -v shows per-stage progress
• All existing tests pass (python -m pytest tests/ -v)

See CONTRIBUTING.md.