Modernize networking layer and fix category navigation and recipe list bugs

Network layer:
- Replace static CookbookApi protocol with instance-based CookbookApiProtocol
  using async/throws instead of tuple returns
- Refactor ApiRequest to use URLComponents for proper URL encoding, replace
  print statements with OSLog, and return typed NetworkError cases
- Add structured NetworkError variants (httpError, connectionError, etc.)
- Remove global cookbookApi constant in favor of injected dependency on AppState
- Delete unused RecipeEditViewModel, RecipeScraper, and Scraper playground

Data & model fixes:
- Add custom Decodable for RecipeDetail with safe fallbacks for malformed JSON
- Make Category Hashable/Equatable use only `name` so NavigationSplitView
  selection survives category refreshes with updated recipe_count
- Return server-assigned ID from uploadRecipe so new recipes get their ID
  before the post-upload refresh block executes

View updates:
- Refresh both old and new category recipe lists after upload when category
  changes, mapping empty recipeCategory to "*" for uncategorized recipes
- Raise deployment target to iOS 18, adopt new SwiftUI API conventions
- Clean up alerts, onboarding views, and settings

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client/Network/NextcloudApi/NextcloudApi.swift

@@ -6,6 +6,7 @@
 //
 
 import Foundation
+import OSLog
 import SwiftUI
 
 /// The `NextcloudApi` class provides functionalities to interact with the Nextcloud API, particularly for user authentication.
@@ -33,10 +34,10 @@ class NextcloudApi {
             return (nil, error)
         }
         guard let data = data else {
-            return (nil, NetworkError.dataError)
+            return (nil, NetworkError.encodingFailed())
         }
         guard let loginRequest: LoginV2Request = JSONDecoder.safeDecode(data) else {
-            return (nil, NetworkError.decodingFailed)
+            return (nil, NetworkError.decodingFailed())
         }
         return (loginRequest, nil)
     }
@@ -69,10 +70,10 @@ class NextcloudApi {
             return (nil, error)
         }
         guard let data = data else {
-            return (nil, NetworkError.dataError)
+            return (nil, NetworkError.encodingFailed())
         }
         guard let loginResponse: LoginV2Response = JSONDecoder.safeDecode(data) else {
-            return (nil, NetworkError.decodingFailed)
+            return (nil, NetworkError.decodingFailed())
         }
         return (loginResponse, nil)
     }
@@ -107,11 +108,11 @@ class NextcloudApi {
                 userId: data?["userId"] as? String ?? "",
                 userDisplayName: data?["displayName"] as? String ?? ""
             )
-            print(userData)
+            Logger.network.debug("Loaded hover card for user \(userData.userId)")
             return (userData, nil)
         } catch {
-            print(error.localizedDescription)
-            return (nil, NetworkError.decodingFailed)
+            Logger.network.error("Failed to decode hover card: \(error.localizedDescription)")
+            return (nil, NetworkError.decodingFailed())
         }
     }
 }