feat: support uv tool install and document in README

[tcconnally]

Summary

Fixes #99: Add explicit [tool.uv] section to pyproject.toml and document uv tool install as a quick installation method in the README.

Changes

1. pyproject.toml: Add [tool.uv] section with comment documenting uv tool install support
2. README.md: Add "Quick install with uv" section before the "From source" instructions

Usage

# One-command install (no clone needed)
uv tool install git+https://github.com/NVIDIA/skillspector.git

# Update to latest
uv tool update skillspector

Testing

All 621 tests pass. No code changes — packaging metadata only.

[rng1995]

APPROVE — adds a uv tool install quick-start to the README plus a [tool.uv] section, with no behavioral risk.

Minor / optional (non-blocking):

• The [tool.uv] section is comment-only/empty, so it does not actually change anything — uv tool install git+... already works because the package defines a [project.scripts] entry point. The README docs are the valuable part; the empty section could be dropped, or a real setting added if one was intended.
• Nit: the README uses a lowercased skillspector.git while the canonical repo name is SkillSpector; GitHub is case-insensitive here so it works, just flagging for consistency.