feat(session): add theory and coding sections with multi-phase orches…

[vitchenkokir]

…tration

Refactor interview into a session shell with dedicated theory and coding modules, selection spec v2, phase orchestration, merged evaluation, and results/review pages. Includes Judge0 coding runner, Alembic migrations, setup and UI updates, and expanded test coverage.

Description

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
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

Testing

• All existing tests pass (uv run pytest)
• New tests added for new functionality
• Manual testing performed

Checklist

• Code follows the style guidelines (uv run ruff check, uv run ruff format, uv run mypy)
• Self-review completed
• Comments added for complex logic
• Documentation updated (if needed)
• No new warnings generated

Related Issues

Fixes #

Screenshots (if applicable)

Additional Notes