Fix length constraints

app.py

@@ -124,8 +124,8 @@ def process_csv_file(csv_file):
                 continue
             trimmed = series.loc[:last_valid].to_numpy(dtype=np.float32)
             length = trimmed.shape[0]
-            if length < 64 or length > 1024:
-                return None, f"Series '{name}' length {length} invalid. Must be 64 to 1024."
+            if length < 16 or length > 1024:
+                return None, f"Series '{name}' length {length} invalid. Must be 16 to 1024."
             ts_names.append(name)
             ts_list.append(trimmed)