Stop flagging SEPA members with a running Rücklastschrift-Mahnung as overdue

sepa_debit_overdue fired unconditionally for every overdue SEPA claim past the
grace period, regardless of whether a reminder had already been sent for it --
so a Rücklastschrift-Mahnung created via the reminder mechanism made no
difference to the housekeeper output. Check for an already-sent reminder whose
own payment deadline hasn't expired yet first; if there is one, show a
low-priority "Rücklastschriftklärung läuft" note instead, mirroring the
non-SEPA "reminder_awaiting_deadline" fix. Once that deadline passes without
resolution, the plain sepa_debit_overdue notice returns.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/ccma/rules/scripts/reminder_due.py

@@ -49,7 +49,7 @@ def evaluate(context: RuleContext) -> list[RuleAction]:
         escalation = None
         if days_overdue >= grace_days and not _hold_is_active(claim, context.today):
             if context.member.mandate_active:
-                escalation = _sepa_action(context, claim, claim_id, days_overdue)
+                escalation = _sepa_escalation(context, claim, claim_id, days_overdue)
             else:
                 escalation = _reminder_action(context, claim, claim_id, levels, policy)
         actions.append(escalation or _overdue_action(context, claim, claim_id, due, days_overdue))
@@ -72,6 +72,13 @@ def _overdue_action(context: RuleContext, claim, claim_id: str, due: date, days_
     )
 
 
+def _sepa_escalation(context: RuleContext, claim, claim_id: str, days_overdue: int) -> RuleAction:
+    pending = _latest_pending_reminder(context.contributions.reminders, claim_id, context.today)
+    if pending:
+        return _sepa_awaiting_action(context, claim, claim_id, *pending)
+    return _sepa_action(context, claim, claim_id, days_overdue)
+
+
 def _sepa_action(context: RuleContext, claim, claim_id: str, days_overdue: int) -> RuleAction:
     balance = money_text(claim_balance(context.contributions, claim))
     return task(
@@ -90,6 +97,47 @@ def _sepa_action(context: RuleContext, claim, claim_id: str, days_overdue: int)
     )
 
 
+def _sepa_awaiting_action(
+    context: RuleContext, claim, claim_id: str, reminder: dict, trigger_date: date
+) -> RuleAction:
+    """A Rücklastschrift-Mahnung (or any reminder) was already sent for this SEPA
+    claim and its own deadline hasn't expired yet -- staff already engaged, so this
+    must not keep nagging "check the direct debit" as if nothing had happened."""
+    name = str(reminder.get("name") or "Rücklastschrift")
+    balance = money_text(claim_balance(context.contributions, claim))
+    return task(
+        rule_id=RULE_ID,
+        member=context.member,
+        key_suffix=f"{claim_id}:sepa-awaiting",
+        severity="info",
+        code="sepa_debit_awaiting_deadline",
+        title=f"{context.member.display_name}: {name} versandt, Rücklastschriftklärung läuft",
+        detail=(
+            f"Forderung: {claim.get('title', claim_id)}. Offener Betrag: {balance} EUR. "
+            f"Zahlungsfrist bis {trigger_date.isoformat()} noch nicht abgelaufen."
+        ),
+        due_date=trigger_date,
+    )
+
+
+def _latest_pending_reminder(
+    reminders: list[dict], claim_id: str, today: date
+) -> tuple[dict, date] | None:
+    best: tuple[dict, date] | None = None
+    for item in reminders:
+        if str(item.get("claim_id", "")) != claim_id or str(item.get("status", "")) != "sent":
+            continue
+        try:
+            deadline = date.fromisoformat(str(item.get("payment_deadline", "")))
+        except ValueError:
+            continue
+        if today > deadline:
+            continue
+        if best is None or deadline > best[1]:
+            best = (item, deadline)
+    return best
+
+
 def _reminder_action(context: RuleContext, claim, claim_id: str, levels, policy) -> RuleAction | None:
     reminders = [
         item for item in context.contributions.reminders if str(item.get("claim_id", "")) == claim_id