settings overhaul, many QOL improvements

backend/models.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, String, DateTime, Boolean, Text, Date
+from sqlalchemy import Column, String, DateTime, Boolean, Text, Date, Integer
 from datetime import datetime
 from backend.database import Base
 
@@ -56,4 +56,24 @@ class IgnoredUnit(Base):
 
     id = Column(String, primary_key=True, index=True)
     reason = Column(String, nullable=True)
-    ignored_at = Column(DateTime, default=datetime.utcnow)
+    ignored_at = Column(DateTime, default=datetime.utcnow)
+
+
+class UserPreferences(Base):
+    """
+    User preferences: persistent storage for application settings.
+    Single-row table (id=1) to store global user preferences.
+    """
+    __tablename__ = "user_preferences"
+
+    id = Column(Integer, primary_key=True, default=1)
+    timezone = Column(String, default="America/New_York")
+    theme = Column(String, default="auto")  # auto, light, dark
+    auto_refresh_interval = Column(Integer, default=10)  # seconds
+    date_format = Column(String, default="MM/DD/YYYY")
+    table_rows_per_page = Column(Integer, default=25)
+    calibration_interval_days = Column(Integer, default=365)
+    calibration_warning_days = Column(Integer, default=30)
+    status_ok_threshold_hours = Column(Integer, default=12)
+    status_pending_threshold_hours = Column(Integer, default=24)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)