Add Ntfy notification support

[jcastro]

Summary

• Adds Ntfy as a third notification provider alongside Gotify and Telegram.
• Supports STOPLIGA_NTFY_URL, STOPLIGA_NTFY_TOPIC, optional bearer token, priority, TLS CA, and plain-HTTP override.
• Documents the .env and TOML configuration examples.

Fixes #17.

Validation

• .venv/bin/python -m ruff check src tests
• .venv/bin/python -m ruff format --check src tests
• .venv/bin/python -m mypy src
• .venv/bin/python -m compileall run_stopliga.py src tests
• .venv/bin/python -m pytest -q
• docker build -t stopliga:issue-17-ntfy-test --build-arg VERSION=0.1.25-issue17 .
• docker run --rm stopliga:issue-17-ntfy-test --help

Test Image

Local image built successfully as stopliga:issue-17-ntfy-test.

Pushing ghcr.io/jcastro/stopliga:issue-17-ntfy-test is blocked until the GitHub CLI token has write:packages.

[jcastro]

Closed because the ntfy work has been merged directly into main at 63fe186.

[myde2001]

Please merge