feat: Add organization name and scheduler refresh interval settings

- Superadmin-only organization name setting displayed in dashboard header
- Advanced Options tab with configurable scheduler refresh interval (0 = disabled)
- Make system settings GET endpoint public for frontend reads
- Scheduler reads refresh_seconds from DB dynamically each loop
- Seed default system settings in init_defaults.py

scheduler/db_utils.py

@@ -5,7 +5,7 @@ from datetime import datetime
 import logging
 from sqlalchemy.orm import sessionmaker, joinedload
 from sqlalchemy import create_engine, or_, and_, text
-from models.models import Event, EventMedia, EventException
+from models.models import Event, EventMedia, EventException, SystemSetting
 from dateutil.rrule import rrulestr
 from urllib.request import Request, urlopen
 from datetime import timezone
@@ -168,6 +168,22 @@ def get_active_events(start: datetime, end: datetime, group_id: int = None):
         session.close()
 
 
+def get_system_setting_value(key: str, default: str | None = None) -> str | None:
+    """Fetch a system setting value by key from DB.
+
+    Returns the setting's string value or the provided default if missing.
+    """
+    session = Session()
+    try:
+        setting = session.query(SystemSetting).filter_by(key=key).first()
+        return setting.value if setting else default
+    except Exception as e:
+        logging.debug(f"[Scheduler] Failed to read system setting '{key}': {e}")
+        return default
+    finally:
+        session.close()
+
+
 def format_event_with_media(event):
     """Transform Event + EventMedia into client-expected format"""
     event_dict = {