feat(notifications): localise the rest of the push text (#1037)

[tempus2016]

Refs #1037. Follow-up to #1041: the rest of the push notification text now follows Home Assistant's language.

Newly localised

• Celebration messages (level up, perfect week, streak milestone, all chores done, birthday, challenge / quest completed, inspection passed). These feed both the celebration push and the taskmate_celebration event message, so TTS automations speak them in your language too.
• Recap announcements: the child push, the "N new recaps" push, the grouped parent push, and the period label inside them (week / month name / year / Jul–Sep).
• Month and weekday names: monthly report heading, season champion month, auction dates (So, 4. Okt).
• Name lists: "Malia, Vaiha und Alex".
• Test pushes from the panel: the stand-in names (Tidy room, Movie night, Grandma, …) are translated.

Fixes along the way

• A test push of the auction / streak-freeze types used to send literal {date}, {max_points}, {result_text} and {freezes_left}. They are filled now.
• Strings load at startup and reload on core_config_updated, so changing HA's language takes effect without a restart. Text built outside the dispatcher (celebrations, recaps) no longer depends on a push having gone out first.
• Recaps no longer .capitalize() the label. That turned Jul–Sep into Jul–sep and would mis-capitalise other languages. The English parent message now reads "✨ New September recaps are ready for …".

Non-English recap templates put the period in brackets ("Dein Rückblick ist fertig (September)"), so a week, month, year or range all read naturally.

Translations

da, de, fr, nb, nn, pl, pt, pt-BR. German month names that match English ("April", "September" …) and pure format patterns are allow-listed in locale_english_baseline.json.

Tests

• New: every notification type's test push, in every locale, leaves no {placeholder} and (outside English) no English sample names. Also German dates / months / name lists / recap labels, English fallbacks, and a language change reloading the strings.
• Full suite 3066 passed. Translation parity, data files and ruff pass.