Rewrite MealPlanSyncManager.performSync() (renamed from performInitialSync) to
discover _mealPlanAssignment metadata from all server recipes, not just locally-
known ones. On first sync all recipes are checked; on subsequent syncs only
recipes modified since lastMealPlanSyncDate are fetched (max 5 concurrent).
Trigger meal plan sync from pull-to-refresh on both the recipe and meal plan
tabs, and from the "Refresh all" toolbar button.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Introduces weekly meal planning with a calendar-based tab view, per-recipe
date assignments synced via Nextcloud Cookbook custom metadata, and 30-day
automatic pruning of old entries on load, save, and sync merge.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>