feat: add optional Typer lifecycle adapter

[codeforester]

Summary

• add the optional base-cli[typer] integration with attach_typer(), TyperAdapter, and get_typer_command()
• preserve Typer-native command trees, typed parameters, nested apps, help, completion, dependency injection, and exceptions while reusing the existing Click lifecycle
• add migration docs, an executable example, compatibility tests, and CI coverage without adding Typer to core dependencies

Closes #61

Verification

• python -m pytest (full suite with Typer 0.12–0.25)
• python -m mypy --strict examples/typed_consumer.py
• ./tests/validate.sh