Add migrate_db() to add missing columns to existing servers table

app/app.py

@@ -412,10 +412,30 @@ def usage_color(percent):
 
 # --- Main ---
 
+def migrate_db():
+    """Add any missing columns to existing tables."""
+    import sqlite3
+    conn = sqlite3.connect(DB_PATH)
+    cursor = conn.cursor()
+    cursor.execute("PRAGMA table_info(servers)")
+    existing = {row[1] for row in cursor.fetchall()}
+    migrations = {
+        'url': "ALTER TABLE servers ADD COLUMN url VARCHAR(1024) DEFAULT ''",
+        'notes': "ALTER TABLE servers ADD COLUMN notes TEXT DEFAULT ''",
+    }
+    for col, sql in migrations.items():
+        if col not in existing:
+            cursor.execute(sql)
+            logger.info("Added column '%s' to servers table", col)
+    conn.commit()
+    conn.close()
+
+
 if __name__ == '__main__':
     os.makedirs(os.path.dirname(DB_PATH), exist_ok=True)
     with app.app_context():
         db.create_all()
+        migrate_db()
     logger.info("Database ready at %s", DB_PATH)
 
     # Start collector thread