Fix kg per week/month for exercise progress graphs and remove useless formula

utils.py

@@ -279,11 +279,9 @@ def get_exercise_graph_model(title, estimated_1rm, repetitions, weight, start_da
         best_fit_points = list(zip(y_best_fit, relative_positions))
 
         # Convert the slope from scaled units per day to kg per day
-        slope_kg_per_day = m * (max_e1rm - min_e1rm) / total_span
+        slope_kg_per_day = (max_e1rm - min_e1rm) / total_span
 
         best_fit_formula = {
-            'slope': round(m,1),
-            'intercept': round(b,1),
             'kg_per_week': round(slope_kg_per_day * 7, 1),  # Convert to kg/week
             'kg_per_month': round(slope_kg_per_day * 30, 1)  # Convert to kg/month
         }