Prepare v2.0.3 release

[heckpiet]

What changed

• release Masscan Web Scanner 2.0.3 with an automatic PASS/SKIP precheck
• request sudo once and apply it only to masscan child processes
• keep Python, Selenium and Chromium unprivileged
• use the operating-system ChromeDriver and validate browser/driver major versions
• archive HTTP 403/404 responses and report HTML and screenshot outcomes separately
• preserve archived HTML when screenshot capture fails
• add --version and --no-sudo
• document Kali PEP 668/pipx installation, upgrades, troubleshooting, security and release verification
• include project documentation in the source distribution

Why

Parallel Selenium Manager resolution failed even with a matching system driver,
and running the complete application with sudo conflicts with Chromium's sandbox.
Kali also blocks pip --user under PEP 668. This release makes those requirements
explicit, validates them before scanning and provides a supported one-command run
after pipx installation.

User impact

Users start the scanner normally with:

masscan-webscanner -r helios.txt -p 80,443 --screenshots

The precheck runs automatically and stops before masscan sends packets when a
required dependency or browser/driver compatibility check fails.

Validation

• 30 tests passed with 93.79% coverage
• Ruff lint and formatting checks passed
• wheel and source distribution built successfully
• Twine validated both distributions
• source archive contents verified
• wheel installed in a fresh virtual environment
• masscan-webscanner --version returned 2.0.3
• installed CLI dry-run completed successfully

No real network scan was performed as part of release validation.