feat(recipes): add recipe categories support (v0.8.0)

- New tool: get_recipe_categories() lists available recipe category IDs
- Enhanced create_recipe and update_recipe with optional category_ids parameter
- Extended get_recipe and get_recipes to include category_ids in response
- Updated parse_recipe_full() to extract recipeCategoryIdList from API response
- Extended build_create_params() and build_update_params() to handle category_ids

Recipe categories are managed via recipe.recipeCategoryIdList in mprecipeput API.
Categories are represented as a list of category IDs (e.g. ["category/23431854_2"]).
No direct API endpoint exists for listing all categories; they are discovered from
existing recipes or must be known in advance.

Version: 0.7.5 → 0.8.0
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

SPEC.md

@@ -659,11 +659,30 @@ Löscht einen Kreis und alle zugehörigen Inhalte (Listen, Tasks, Rezepte, Wall-
 
 **Verifiziert am:** 2026-04-16 via FW_DEBUG=1 (family/23447371 erfolgreich gelöscht)
 
+### Recipe Categories API Details
+
+Recipe categories are managed via `mprecipeput` endpoint. Each recipe can have zero or more
+categories assigned via `recipe.recipeCategoryIdList` (sent multiple times for each category).
+
+**Response structure** (in `mprecipeput` response):
+
+```
+a00.r.r
+  .recipeCategoryIdList[]   → List of assigned category IDs (e.g. ["category/23431854_2"])
+  .recipeCategories[]       → List of system names (e.g. ["KIDS_LOVE"])
+```
+
+**Category IDs** have format `category/<family_id>_<index>`. Categories are family-wide.
+Premium accounts have additional categories beyond the 5 available in free tier.
+
+**Limitation:** Currently no API endpoint to list all available categories. Categories are
+discovered by examining existing recipes or hardcoding known IDs.
+
 ## Offene Punkte
 
 - Unlike-Endpoint (Service Worker blockiert Analyse)
 - Erinnerungen (reminder) – nur Premium-Account
 - Wiederholungen (repeat) – nur Premium-Account
-- Sortierung von Kategorien via API
+- Rezept-Kategorien-Listing-Endpoint (derzeit keine API, müssen aus Rezepten extrahiert werden)
 - mpadditemtolist (Zutaten aus Rezept → Einkaufsliste)
 - Einladung bestehender FamilyWall-Nutzer (accinvite nur für neue Accounts)