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>

frontend/playwright.config.ts

@@ -0,0 +1,12 @@
+import type { PlaywrightTestConfig } from '@playwright/test';
+
+const config: PlaywrightTestConfig = {
+	webServer: {
+		command: 'npm run build && npm run preview',
+		port: 4173
+	},
+	testDir: 'e2e',
+	testMatch: /(.+\.)?(test|spec)\.[jt]s/
+};
+
+export default config;