Add and normalize HRT technical assessment problems

[eselyavka]

Summary

• add as a grouped assessment module
• normalize the module to match the repo’s assessment style with module docs, clearer naming, and coverage
• include three problems in :
  • hollow square rendering
  • bus commute round-trip scheduling
  • board layout validation
• update to document representative technical assessment files and the current problem set
• align the README test command with the repo’s expected Python 3.11 virtualenv

Testing

• ============================= test session starts ==============================
  platform darwin -- Python 3.11.12, pytest-9.0.2, pluggy-1.6.0
  rootdir: /Users/eseliavka/projects/python
  configfile: pyproject.toml
  collected 11 items

technical_assessments/hrt.py ........... [100%]

============================== 11 passed in 0.01s ==============================

• pre-commit hook: full repo and on changed Python files