Rework the Pushover/Apprise summary so it reads as a report instead of a
dump of counters.
- Extract build_summary() as the single source of truth for both notifiers,
removing the duplicated body string and the stray leading indentation
caused by backslash line continuations.
- Add a 'format' option: 'plain' (aligned columns) or 'html' (bold labels,
sets html=1 for Pushover). Apprise always receives the plain body.
- Add 'use_emoji' for emoji-prefixed rows.
- Title now states the outcome ('7 torrents removed') instead of
'--- qbit-maid summary ---'.
- Say 'Would remove' when delete_torrents is false, so a dry run is never
mistaken for a real deletion.
- Format runtime as 12s / 1m 04s instead of a timedelta with microseconds.
- Add include_hostname, notify_on_empty, priority, sound, retry and expire.
- Log notification failures instead of letting them abort the run.
- Cover the new formatting with unit tests; document the options in the
README and config.toml.example.
