fix: fix menu generation errors and show planned meals on home screen

Backend fixes:
- migration 003: add 'menu' value to recipe_source enum (was causing SQLSTATE 22P02)
- migration 004: rename recipe_products→recipe_ingredients, product_id→ingredient_id (was causing SQLSTATE 42P01)
- dish/repository.go: fix INSERT INTO tags using $1/$1 for two columns → $1/$2 (was causing SQLSTATE 42P08)
- home/handler.go: replace non-existent saved_recipes table with correct joins (recipes→dishes→dish_translations, user_saved_recipes) so today's plan and recommendations load correctly
- reqlog: new slog.Handler wrapper that adds request_id and stack trace to ERROR-level logs
- all handlers: slog.Error→slog.ErrorContext so error logs include request context; writeError includes request_id in response body

Client:
- home_screen.dart: extend home screen to future dates, show planned meals as ghost entries
- l10n: add new localisation keys for home screen date navigation and planned meal UI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/l10n/app_localizations_it.dart

@@ -357,8 +357,21 @@ class AppLocalizationsIt extends AppLocalizations {
   }
 
   @override
-  String get markAsEaten => '';
+  String get markAsEaten => 'Segna come mangiato';
 
   @override
-  String get plannedMealLabel => '';
+  String get plannedMealLabel => 'Pianificato';
+
+  @override
+  String get generateWeekLabel => 'Pianifica la settimana';
+
+  @override
+  String get generateWeekSubtitle =>
+      'L\'AI creerà un menu con colazione, pranzo e cena per tutta la settimana';
+
+  @override
+  String get generatingMenu => 'Generazione menu...';
+
+  @override
+  String get weekPlannedLabel => 'Settimana pianificata';
 }