feat(export): add PDF report generator and --format pdf option

[kaifcodec]

Description

Adds a PDF report generator feature to user-scanner.

Key Changes

• PDF Generator Module (user_scanner/core/pdf_generator.py): Built with ReportLab, Pillow, and Svglib. Generates an Intelligence Dossier containing header details with tool version, target summary box, identified profile media grid (60x60 square cropped avatars), digital footprint mapping table, and extracted deep intelligence cards with proper vertical leading to prevent text overlap.
• Formatter Helper (user_scanner/core/formatter.py): Added into_pdf wrapper function.
• CLI Export Support (user_scanner/__main__.py): Updated -f / --format choices to accept pdf, auto-detected .pdf file extensions, and added --no-pdf-media flag option to skip avatar downloads if needed.
• Optional Dependencies (pyproject.toml): Defined pdf = ["reportlab>=4.0.0", "pillow>=10.0.0", "svglib>=1.5.0"].
• Unit Tests (tests/test_pdf_generator.py): Comprehensive test suite covering PDF generation, magic byte verification, header version display, and missing dependency fallbacks.

[kristoisberg]

When testing the snapcode question I noticed some issues with link rendering:
user-scanner -f pdf -u asdfg -m snapchat

Checking username: asdfg
[✔] Snapchat (asdfg): Found
└── snapcode: https://app.snapchat.com/web/deeplink/snapcode?username=asdfg&type=SVG&bitmoji=enable

But it is rendered in the report as follows:

Only the first line is clickable, and some characters are added that shouldn't be there.

Looks great otherwise!

[kaifcodec]

@kristoisberg The issue happened because ReportLab’s Paragraph component parses text input as HTML/XML. When a URL contains unescaped ampersands (&), ReportLab mistakes them for XML entities and automatically injects semicolons, turning &type into &type;= and breaking the link.

Wrapping the raw URL strings with html.escape() before passing them to Paragraph ensures & is properly handled as &, keeping the URL intact without any unwanted semicolons.

I pushed the fix in (31e9326).

[VamatoHD]

LGTM