feat: improve scheduler recurrence, DB config, and docs

- Broaden scheduler query window to next N days for proper recurring event expansion (scheduler.py)
- Update DB connection logic for consistent .env loading and fallback (database.py)
- Harden timezone handling and logging in scheduler and DB utils
- Stop auto-deactivating recurring events before recurrence_end (API/events)
- Update documentation to reflect new scheduler, API, and logging behavior

scheduler/scheduler.py

@@ -37,6 +37,8 @@ def main():
     POLL_INTERVAL = 30  # Sekunden, Empfehlung für seltene Änderungen
     # 0 = aus; z.B. 600 für alle 10 Min
     REFRESH_SECONDS = int(os.getenv("REFRESH_SECONDS", "0"))
+    # Konfigurierbares Zeitfenster in Tagen (Standard: 7)
+    WINDOW_DAYS = int(os.getenv("EVENTS_WINDOW_DAYS", "7"))
     last_payloads = {}       # group_id -> payload
     last_published_at = {}   # group_id -> epoch seconds
 
@@ -55,8 +57,17 @@ def main():
 
     while True:
         now = datetime.datetime.now(datetime.timezone.utc)
+        # Query window: next N days to capture upcoming events and recurring instances
+        # Clients need to know what's coming, not just what's active right now
+        end_window = now + datetime.timedelta(days=WINDOW_DAYS)
+        logging.debug(f"Fetching events window start={now.isoformat()} end={end_window.isoformat()} (days={WINDOW_DAYS})")
         # Hole alle aktiven Events (bereits formatierte Dictionaries)
-        events = get_active_events(now, now)
+        try:
+            events = get_active_events(now, end_window)
+            logging.debug(f"Fetched {len(events)} events for publishing window")
+        except Exception as e:
+            logging.exception(f"Error while fetching events: {e}")
+            events = []
 
         # Gruppiere Events nach group_id
         groups = {}
@@ -67,6 +78,9 @@ def main():
             # Event ist bereits ein Dictionary im gewünschten Format
             groups[gid].append(event)
 
+        if not groups:
+            logging.debug("No events grouped for any client group in current window")
+
         # Sende pro Gruppe die Eventliste als retained Message, nur bei Änderung
         for gid, event_list in groups.items():
             # stabile Reihenfolge, um unnötige Publishes zu vermeiden
@@ -87,7 +101,7 @@ def main():
                     logging.error(
                         f"Fehler beim Publish für Gruppe {gid}: {mqtt.error_string(result.rc)}")
                 else:
-                    logging.info(f"Events für Gruppe {gid} gesendet")
+                    logging.info(f"Events für Gruppe {gid} gesendet (count={len(event_list)})")
                     last_payloads[gid] = payload
                     last_published_at[gid] = time.time()