feat: add cookbooks, multiple categories, and image management

Major features added:
- Cookbook management with CRUD operations
- Auto-filter cookbooks by categories and tags
- Multiple categories per recipe (changed from single category)
- Image upload and URL download for cookbooks
- Improved image management UI

Database changes:
- Changed Recipe.category (string) to Recipe.categories (string array)
- Added Cookbook and CookbookRecipe models
- Added Tag and RecipeTag models for recipe tagging

Backend changes:
- Added cookbooks API routes with image upload
- Added tags API routes
- Added auto-filter functionality to add recipes to cookbooks automatically
- Added downloadAndSaveImage() to StorageService for URL downloads
- Updated recipes routes to support multiple categories

Frontend changes:
- Added Cookbooks page with grid view
- Added CookbookDetail page with filtering
- Added EditCookbook page with image upload/download
- Updated recipe forms to use chip-based UI for multiple categories
- Improved image upload UX with separate file upload and URL download
- Added remove image functionality with immediate save

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

packages/api/prisma/schema.prisma

@@ -20,7 +20,7 @@ model Recipe {
   sourceUrl   String?  // For imported recipes
   author      String?
   cuisine     String?
-  category    String?
+  categories  String[] @default([])  // Changed from single category to array
   rating      Float?
   createdAt   DateTime @default(now())
   updatedAt   DateTime @updatedAt
@@ -30,10 +30,10 @@ model Recipe {
   instructions Instruction[]
   images       RecipeImage[]
   tags         RecipeTag[]
+  cookbooks    CookbookRecipe[]
 
   @@index([title])
   @@index([cuisine])
-  @@index([category])
 }
 
 model RecipeSection {
@@ -127,3 +127,32 @@ model RecipeTag {
   @@index([recipeId])
   @@index([tagId])
 }
+
+model Cookbook {
+  id            String   @id @default(cuid())
+  name          String
+  description   String?
+  coverImageUrl String?
+  autoFilterCategories String[] @default([])  // Auto-add recipes matching these categories
+  autoFilterTags       String[] @default([])  // Auto-add recipes matching these tags
+  createdAt     DateTime @default(now())
+  updatedAt     DateTime @updatedAt
+
+  recipes CookbookRecipe[]
+
+  @@index([name])
+}
+
+model CookbookRecipe {
+  id         String   @id @default(cuid())
+  cookbookId String
+  recipeId   String
+  addedAt    DateTime @default(now())
+
+  cookbook Cookbook @relation(fields: [cookbookId], references: [id], onDelete: Cascade)
+  recipe   Recipe   @relation(fields: [recipeId], references: [id], onDelete: Cascade)
+
+  @@unique([cookbookId, recipeId])
+  @@index([cookbookId])
+  @@index([recipeId])
+}