Add repeat_every (fixed-schedule) mode with guided multi-step flow alongside existing repeat_after (completion-coupled) mode

[Copilot]

• Fix DONE no-op for all callers (previous task)
• sensor.py: Emit only mode-relevant attributes — repeat_after → task_interval_value/type; repeat_every → repeat_every_type + only the sub-fields for that type; no more Unknown values for irrelevant attrs
• Translations (strings.json, en.json, de.json): Added keys for schedule, every, on, day_of_month_prefix, of_month, days_before_end_of_month_singular/plural, last_day_of_month, weekday names, occurrence_1/2/3/4/last
• task-tracker-card.js: Added _scheduleStr() helper; repeat_after shows "Interval: 7 Days"; repeat_every shows human-readable "Schedule: Every 2 Weeks on Monday" / "Day 15 of month" / "1st Monday of month" / "5 days before end of month" etc.
• task-tracker-panel.js: Same _scheduleStr() helper in _renderTaskCard
• All 233 unit tests pass

[gensyn]

@copilot While this solution probably works, this is a very minimalistic approach and not very user friendly. I would prefer a solution that supports the following for repeat_every:

• repeat every nth [monday ... sunday]
• repeat on every nth day of the month
• repeat every nth [monday ... sunday] of the month

With this functionality, repeat_after and repeat_every would need fundamentally different options and could not be entered into the existing config_flow. Is there a way to first ask what kind of functionality is needed and then present different options based on the selection?

[Copilot]

@copilot While this solution probably works, this is a very minimalistic approach and not very user friendly. I would prefer a solution that supports the following for repeat_every:

• repeat every ...

Done in commit 11373ab. The repeat_every mode now supports three calendar-based schedule types, presented via a guided multi-step flow:

Step 1 – name + repeat mode (repeat_after or repeat_every)

For repeat_after (step 2a):

• Interval value + unit (day/week/month/year) — same as before

For repeat_every (step 2b → step 3):

• Every N weeks on a weekday – pick weekday (Mon–Sun) + interval (e.g. every Wednesday, every other Monday)
• Every Nth day of the month – pick day 1–31 (clamped to month length, e.g. day 31 → Feb 28/29)
• Every Nth weekday of the month – pick weekday + occurrence (1st, 2nd, 3rd, 4th, last) — e.g. "2nd Monday" or "last Friday"

The coordinator async_mark_as_done already uses due_date (not today) for repeat_every, so the schedule stays anchored after each completion regardless of when the task was checked off.