docs: sync README with docker-compose, helm, and notebooks

[SongHyeopPark]

📝 Description

Sync root README.md with the current deployment assets so the top-level guide matches the actual runtime setup.

Main updates:

• align service architecture section with current components (including envector-shaper)
• align Docker Compose quick-start and key environment variable names with ENVECTOR_*
• align Kubernetes section with current Helm chart usage, license secret flow, and External Secrets options
• align Python SDK/notebooks references with current pyenvector usage

🔍 Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Configuration changes
• 🚀 Deployment/Infrastructure changes
• 📓 Example code improvements

📋 Checklist

• I have performed a self-review of my changes
• I have made corresponding changes to the documentation
• I have tested the deployment configuration locally (if applicable)
• I have verified the example code runs correctly
• I have updated version numbers if applicable
• Configuration files are properly formatted and valid

📸 Screenshots

N/A (documentation-only change)

🔗 Related Issues

N/A

📚 Additional Notes

No runtime config or manifest files were changed in this PR; this is a docs sync only.

📋 Review Checklist for Maintainers

• Documentation is updated and accurate
• Deployment configurations are tested and working
• Example code is clear and functional
• Security considerations have been addressed
• Breaking changes are clearly documented
• Dependencies are appropriate and up-to-date
• Configuration files are properly formatted and valid