fix(pdf): isolate batch scans into separate pdf reports

[kaifcodec]

Fixes #596.

This PR restructures the batch processing and cross-scan execution loops in __main__.py. Instead of accumulating all batch targets into a single list and attempting to render them into a single PDF (which caused empty pages and data collision), the engine now natively processes each seed target in isolation.

Key Changes:

• Loops over targets_found and fully executes both standard modules and cross-scans per target.
• Tags all results with an internal seed_target marker.
• The PDF exporter now natively reads this marker and saves a separate PDF file (e.g. johndoe_report.pdf, kaifcodec_report.pdf) for every seed target in the batch.
• Cross-scanned pivots remain grouped perfectly underneath the parent seed target that spawned them.