fix: add missing validation_rules in migration 013 (#15)

SQL Error: VALUES lists must all be the same length (line 130)
Cause: kcal_per_km row was missing validation_rules JSONB value

Fixed: Added validation_rules '{"min": 0, "max": 1000}'::jsonb

All 16 parameter rows now have correct 10 columns:
key, name_de, name_en, category, data_type, unit, source_field,
validation_rules, description_de, description_en

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/migrations/013_training_parameters.sql

@@ -128,6 +128,7 @@ INSERT INTO training_parameters (key, name_de, name_en, category, data_type, uni
  'Average heart rate as percentage of max heart rate'),
 
 ('kcal_per_km', 'Kalorien pro km', 'Calories per km', 'performance', 'float', 'kcal/km', 'kcal_per_km',
+ '{"min": 0, "max": 1000}'::jsonb,
  'Kalorienverbrauch pro Kilometer',
  'Calorie burn per kilometer');