initialize rates setting

api/database.py

@@ -77,6 +77,13 @@ def initialize_db() -> None:
             """
         )
 
+        # Initialize default settings
+        # Use JSON string for array values
+        cursor.execute(
+            "INSERT OR REPLACE INTO settings (name, value) VALUES (?, ?)",
+            ("rate_options", json.dumps(["half_hour", "hour"])),
+        )
+
         conn.commit()
 
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