feat(anhaenge): attachment_count im Termin-JSON

Die Terminliste traegt nur die Anzahl, nicht die Anhaenge selbst. Der
Merge-Read laeuft pro Termin durch eine Schleife -- eine Lazy-Relationship
waere dort eine Abfrage je Termin ueber eine ganze Monatsansicht, und ein
wiederkehrender Termin wuerde dieselbe Liste an jeder Instanz wiederholen.
Stattdessen je Kalender eine gruppierte Abfrage; die Liste holen die
Clients beim Oeffnen der Detailansicht.

mask_busy_event setzt die Zahl ausdruecklich auf 0: dass ein als
"Beschaeftigt" maskierter Termin drei Dateien haette, ist auch eine
Information.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/routers/caldav_router.py

@@ -9,6 +9,7 @@ from pydantic import BaseModel
 from sqlalchemy.orm import Session
 from sqlalchemy import or_
 
+import attachments_store
 import caldav_client
 import models
 import permissions
@@ -400,6 +401,9 @@ def get_events(
             )
             .all()
         )
+        # One grouped query for the whole calendar: a per-event lookup here
+        # would be N+1 across a month view.
+        att_counts = attachments_store.counts_for_events(db, [e.id for e in local_events])
         for ev in local_events:
             creator = resolve_creator(ev, name_cache=name_cache)
             # A private event belonging to someone else (shared calendar or group
@@ -413,9 +417,15 @@ def get_events(
             if foreign_private and visibility == "hidden":
                 continue
             if ev.rrule:
-                built = expand_recurring_local(ev, local_cal, start_dt, end_dt, creator=creator)
+                built = expand_recurring_local(
+                    ev, local_cal, start_dt, end_dt, creator=creator,
+                    attachment_count=att_counts.get(ev.id, 0),
+                )
             else:
-                built = [build_local_event_dict(ev, local_cal, rrule=None, creator=creator)]
+                built = [build_local_event_dict(
+                    ev, local_cal, rrule=None, creator=creator,
+                    attachment_count=att_counts.get(ev.id, 0),
+                )]
             for b in built:
                 if shared_owner_name:
                     b["calendar_name"] = shared_owner_name

backend/routers/groups_router.py

@@ -398,6 +398,7 @@ def combined_events(
             )
             .all()
         )
+        att_counts = attachments_store.counts_for_events(db, [e.id for e in events])
         for ev in events:
             creator_owner_id = ev.creator_id or owner_id
             # Private filtering for events that belong to someone else.
@@ -412,9 +413,9 @@ def combined_events(
                 creator = {"id": None, "display_name": f"{ev.creator_name_external} (importiert)"}
 
             if ev.rrule:
-                built = expand_recurring_local(ev, cal, start_dt, end_dt, creator=creator, owner=owner, is_group_event=is_group, read_only=read_only)
+                built = expand_recurring_local(ev, cal, start_dt, end_dt, creator=creator, owner=owner, is_group_event=is_group, read_only=read_only, attachment_count=att_counts.get(ev.id, 0))
             else:
-                built = [build_local_event_dict(ev, cal, rrule=None, creator=creator, owner=owner, is_group_event=is_group, read_only=read_only)]
+                built = [build_local_event_dict(ev, cal, rrule=None, creator=creator, owner=owner, is_group_event=is_group, read_only=read_only, attachment_count=att_counts.get(ev.id, 0))]
 
             for b in built:
                 if ev.is_private and creator_owner_id != current_user.id and visibility_for(creator_owner_id) == "busy":

backend/routers/local_router.py

@@ -110,7 +110,11 @@ def _cal_dict(cal: models.LocalCalendar, *, owned: bool = True,
 
 
 def _event_dict(ev: models.LocalEvent, cal: models.LocalCalendar, db: Session) -> dict:
-    return build_local_event_dict(ev, cal, creator=resolve_creator(ev))
+    counts = attachments_store.counts_for_events(db, [ev.id])
+    return build_local_event_dict(
+        ev, cal, creator=resolve_creator(ev),
+        attachment_count=counts.get(ev.id, 0),
+    )
 
 
 # ── Calendar CRUD ─────────────────────────────────────────