docs: Update README

[awinml]

Summary

Update README badges to replace stale individual workflow badges with consolidated CI badges. Also adds ty badge to reflect the mypy → ty migration.

Changes

• README.md: Replaced stale code_checks.yml and tests.yml badges with consolidated ci.yml badges.
  • CI - consolidated workflow status
  • Ruff - linting/formatting
  • ty - type checking (replaces mypy)
  • Bandit - security scanning
  • Tests - test suite status

Checklist

• Code follows project style (make lint-check)
• Type annotations pass (make lint-typing)
• No typos (make lint-typos)
• No new security issues (make security-bandit)
• Dependency vulnerabilities checked (make security-audit)
• Pre-commit hooks pass (uv run pre-commit run --all-files)

[gemini-code-assist]

Code Review

This pull request updates the badges in the README.md file to point to the consolidated ci.yml workflow. The reviewer pointed out that because Shields.io's GitHub Actions status badge does not support filtering by individual jobs, all of the newly added badges (Ruff, ty, Bandit, Tests) will display as failing if any single job fails. It is recommended to keep only the consolidated CI badge.