feat(recipes): add image upload, fix save 500, seed HelloFresh data

- Store hero image as base64 data URI in text column (V023 migration)
- Add file upload UI to RecipeForm with FileReader preview
- Remove isChildFriendly from RecipeCreateRequest (no form field)
- Fix 500 on save: effort values now lowercase, serves/cookTimeMin changed
  from primitive short to nullable Integer to survive omitted fields
- Fix empty categories panel: removed stale tagType=category filter
- Group category tags by type with German headings in recipe form
- Split SuggestionResponse.SuggestionRecipe (no image) from SlotRecipe
- Seed 11 HelloFresh recipes with ingredients, steps and tags (V101)
- Add frontend e2e scaffold, specs and dev yml

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

backend/src/test/java/com/recipeapp/planning/WeekPlanControllerTest.java

@@ -161,7 +161,7 @@ class WeekPlanControllerTest {
 
     @Test
     void getSuggestionsShouldReturn200() throws Exception {
-        var recipe = new SlotResponse.SlotRecipe(UUID.randomUUID(), "Stir Fry", "easy", (short) 15, null);
+        var recipe = new SuggestionResponse.SuggestionRecipe(UUID.randomUUID(), "Stir Fry", "easy", (short) 15);
         var item = new SuggestionResponse.SuggestionItem(recipe, 1.5, false);
         var response = new SuggestionResponse(List.of(item));
 

backend/src/test/java/com/recipeapp/recipe/RecipeControllerTest.java

@@ -165,7 +165,7 @@ class RecipeControllerTest {
     private RecipeCreateRequest sampleCreateRequest() {
         var ingredientId = UUID.randomUUID();
         return new RecipeCreateRequest(
-                "Spaghetti Bolognese", (short) 4, (short) 45, "medium", true, null,
+                "Spaghetti Bolognese", 4, 45, "medium", null,
                 List.of(new RecipeCreateRequest.IngredientEntry(
                         ingredientId, null, new BigDecimal("400"), "g", (short) 1)),
                 List.of(new RecipeCreateRequest.StepEntry((short) 1, "Boil water.")),

backend/src/test/java/com/recipeapp/recipe/RecipeServiceTest.java

@@ -126,7 +126,7 @@ class RecipeServiceTest {
         });
 
         var request = new RecipeCreateRequest(
-                "Spaghetti Bolognese", (short) 4, (short) 45, "medium", true, null,
+                "Spaghetti Bolognese", 4, 45, "medium", null,
                 List.of(new RecipeCreateRequest.IngredientEntry(
                         ingredient.getId(), null, new BigDecimal("400"), "g", (short) 1)),
                 List.of(new RecipeCreateRequest.StepEntry((short) 1, "Boil water.")),
@@ -166,7 +166,7 @@ class RecipeServiceTest {
         });
 
         var request = new RecipeCreateRequest(
-                "Carbonara", (short) 2, (short) 30, "medium", false, null,
+                "Carbonara", 2, 30, "medium", null,
                 List.of(new RecipeCreateRequest.IngredientEntry(
                         null, "pancetta", new BigDecimal("100"), "g", (short) 1)),
                 List.of(),
@@ -192,7 +192,7 @@ class RecipeServiceTest {
         when(recipeRepository.save(any(Recipe.class))).thenAnswer(i -> i.getArgument(0));
 
         var request = new RecipeCreateRequest(
-                "Chicken Rice", (short) 3, (short) 25, "easy", true, null,
+                "Chicken Rice", 3, 25, "easy", null,
                 List.of(new RecipeCreateRequest.IngredientEntry(
                         ingredient.getId(), null, new BigDecimal("300"), "g", (short) 1)),
                 List.of(new RecipeCreateRequest.StepEntry((short) 1, "Cook rice.")),
@@ -450,7 +450,7 @@ class RecipeServiceTest {
         when(householdRepository.findById(HOUSEHOLD_ID)).thenReturn(Optional.empty());
 
         var request = new RecipeCreateRequest(
-                "Test", (short) 2, (short) 15, "easy", false, null,
+                "Test", 2, 15, "easy", null,
                 List.of(), List.of(), List.of());
 
         assertThatThrownBy(() -> recipeService.createRecipe(HOUSEHOLD_ID, request))
@@ -466,7 +466,7 @@ class RecipeServiceTest {
         when(ingredientRepository.findById(ingredientId)).thenReturn(Optional.empty());
 
         var request = new RecipeCreateRequest(
-                "Test", (short) 2, (short) 15, "easy", false, null,
+                "Test", 2, 15, "easy", null,
                 List.of(new RecipeCreateRequest.IngredientEntry(
                         ingredientId, null, new BigDecimal("100"), "g", (short) 1)),
                 List.of(), List.of());
@@ -491,7 +491,7 @@ class RecipeServiceTest {
         });
 
         var request = new RecipeCreateRequest(
-                "Simple", (short) 1, (short) 5, "easy", false, null,
+                "Simple", 1, 5, "easy", null,
                 null, null, null);
 
         RecipeDetailResponse result = recipeService.createRecipe(HOUSEHOLD_ID, request);
@@ -518,7 +518,7 @@ class RecipeServiceTest {
                 .thenReturn(Optional.empty());
 
         var request = new RecipeCreateRequest(
-                "Updated", (short) 2, (short) 20, "easy", false, null,
+                "Updated", 2, 20, "easy", null,
                 List.of(), List.of(), List.of());
 
         assertThatThrownBy(() -> recipeService.updateRecipe(HOUSEHOLD_ID, id, request))