curses: show probe protocol in title

[Komzpa]

Summary

• add the active probe protocol to the curses title line
• update the title automatically after switching with t or u, since redraw reads the current mtrtype

Fixes #482.

Validation

• git diff --check
• ./bootstrap.sh
• ./configure --without-gtk --without-jansson
• make -j "$(nproc)"
• uv run --python 3.9 --with flake8==3.9.2 --with flake8-bandit==2.1.2 --with bandit==1.7.2 --with pbr==7.0.3 python -m flake8 .
• sudo python3 ./test/cmdparse.py

[Komzpa]

Superseded by #576, which now carries the curses title context together with the related curses display polish.