docs(readme): professional rewrite with badges, categories, full reference

- Centered hero with 8 shields.io badges (release, tests, zero-deps, last-commit,
  license, node, npm, stars, docs link, changelog, PRs, VS Code extension)
- Table of contents linking every major section
- 16 organized sections with emoji headers
- VS Code extension section (new)
- Security scanning section with pattern table (new)
- MCP tools table with all 7 tools
- Languages table expanded with 'Extracts' column
- Context strategies with comparison table
- Configuration with output-targets table
- Project structure as annotated directory tree
- Principles table (was bullet list)
- Contributing section with extractor contract
- Remove ~370 lines of duplicate old content

Author: manojmallick