Handle long task names in --list output

[cyphercodes]

Summary

• Prevent --list column wrapping from using a non-positive description width when task names consume the terminal width.
• Add a regression test covering an issue-length task name at 80 columns.

Verification

• uv run pytest tests/program.py -k long_task_names_may_exhaust_terminal_width
• uv run pytest tests/program.py
• uv run inv test
• uv run flake8 --exclude=.venv,invoke/vendor,sites,.git,build,dist,alt_env,appveyor,.cci_pycache .
• uv run mypy invoke/program.py
• git diff --check

Fixes #1071

[cyphercodes]

Pushed a tiny coverage-hygiene follow-up for the Codecov patch failure.

Change:

• Marked the dummy task body in the new --list regression test as # pragma: no cover, since --list intentionally inspects the task metadata without executing that body.

Local verification:

• uv run flake8 tests/program.py ✅
• uv run pytest tests/program.py -q ✅ (122 passed, 2 skipped)
• git diff --check ✅