docs: complete README tool reference

[chriswu727]

What changed

• make uvx the zero-install quick-start path while retaining the pip alternative
• document all 29 core, 14 screen, and 76 full-profile public tools
• explain profile selection and the --unsafe requirement for eval_js
• add a release-metadata test that fails when public tools or profile counts drift from the README

Why

The 0.5.0 README described the primary workflow but did not enumerate every public tool or the real profile sizes. This made the package documentation current but incomplete and allowed future tool changes to drift silently.

Verification

• 238 tests passed across four bounded groups: 68 + 28 + 122 + 20
• tests/test_release_metadata.py: 2 passed
• public PyPI argus-testing==0.5.0 exposes 29 core tools
• Playwright uvx command resolves without warnings
• git diff --check passed